The Quinnipiac poll shows Blumenthal's margin over McMahon narrowing to just three points (49% to 46%), a slightly closer margin than on their previous poll earlier in the month (51% to 45%). Rasmussen Reports also released a new Connecticut poll yesterday that showing Blumenthal ahead by just five points (50% to 45%), a slightly closer than the 9-point margin they found earlier in September (53% to 44%). The new surveys narrow Blumenthal's lead on our trend estimate to just four percentage points (49.8% to 45.3%), shifting the race to "lean Democrat" status.

The Blumenthal campaign will likely quarrel with these numbers, as they preemptively shared results of an internal poll yesterday with other media outlets, purportedly showing their candidate with a double-digit lead. But while the levels of support measured by the Quinnipiac and Rasmussen surveys may or may not be right, the trend evident in their results is unmistakable: McMahon has narrowed the gap significantly since winning the Republican primary in August.

Elsewhere, two new polls in Pennsylvania produced results consistent with previous data. In the Senate race, a new Muhlenberg College/Morning Call poll shows Republican Pat Toomey leading Democrat Joe Sestak by 7 points (46% to 39%), while a new automated survey by the Republican firm Magellan Data and Mapping puts Toomey ahead by 8 (49% to 41%). That makes 18 public polls in a row since July showing Toomey with a nominal lead. Our more sensitive trend line shows that while voters have been growing increasingly decided, the roughly 7-8 point margin between Toomey and Sestak has not changed since August.

In the Pennsylvania governor's race, the Muhlenberg College poll shows Republican Tom Corbett leading Democrat Dan Onorato by 9 points (48% to 37%), while the Magellan poll has Corbett up by 12 (50% to 38%). Corbett's margin on the Muhlenberg result is one of the narrower reported in recent weeks. Our trend estimate gives Corbett a roughly 12-point advantage (50.3% to 38.7%).

In Delaware, Rasmussen Reports' latest poll shows Democrat Chris Coons leading Republican Christine O'Donnell by 9 points (49% to 40%), a slightly narrower margin than the CNN/Time poll found a week ago (55% to 39%).

The Rasmussen poll also found 5% support for Mike Castle, the incumbent Senator who lost the Republican primary to O'Donnell earlier this month. Castle is said to be considering a write-in candidacy. Rasmussen's approach was to omit reference to Castle in the first part of the question, but offer him as a option in the second. If the answer categories followed Rasmussen's typical format, their respondents would have heard something like this:

If the 2010 Election for United States senate, were held today would you vote for Republican Christine O'Donnell or Democrat Chris Coons?
If you are for O'Donnell, press 1
If you are for Coons, press 2
If you are for Mike Castle, press 3
If you are for someone else, press 4
If you are not sure, press 5

In this case, if the Rasmussen system allows respondents to answer immediately (without waiting to hear all the choices), many would have chosen O'Donnell or Coons before hearing that Castle was an option. Measuring support for a write-in candidacy is difficult, especially when it is still hypothetical. This sort of question will tend to measure the floor of a write-in candidate's support. So don't be surprised if other Delaware polls in the near future offer Castle as a more explicit option and show more potential support.

[Cross-posted to the Huffington Post]

A new Field poll of California released this morning shows Boxer leading Fiorina by six percentage points (47% to 41%), while a new automated SurveyUSA poll yields fewer undecided voters but gives Boxer the same six-point advantage (49% to 43%). A handful of automated surveys in late August and early September suggested a tighter race, including two earlier polls from SurveyUSA that gave Fiorina a slight edge, but the last five surveys conducted since mid-September all show Boxer with nominal leads.

Our standard trend estimate, based on all available public polls, now shows Boxer leading by a roughly three-point margin (47.5% to 44.3%). Our more sensitive trend line, shown below, illustrates the tightening in late August. Since the current estimate from that line gives greater weight to more recent polls, it gives Boxer a slightly larger lead (47.8% to 43.2%).

The two new California polls also suggest a reversal of the previous trend favoring Republican Meg Whitman. The Field poll results released yesterday show Whitman tied with Democrat Jerry Brown (at 41% each), while SurveyUSA gives Brown a small but statistically insignificant advantage (46% to 43%). So while six surveys had shown Brown with nominal leads in August and early September, the five most recent polls show either a tie or a slight Brown edge.

Our standard estimate shows a slight Whitman lead (45.9% to 44.4%), but our more sensitive trend line points puts Brown ahead by a single percentage point (45.5% to 44.1%). Either way, the California governor's race is currently the closest in the nation.

SurveyUSA also released a new data this week in Washington confirming a similar rebound by Democratic Senator Patty Murray over Republican challenger Dino Rossi. The new automated poll gives Murray a two-point edge (50% to 48%), a marked improvement from their last survey in mid-August showing Rossi leading by seven. Our trend estimate now shows Murray ahead by roughly five points (50.8% to 45.8%), as all four surveys released in the last two weeks show Murray at least nominally ahead. Rossi continues to do slightly better on automated surveys by SurveyUSA and Rasmussen than on live interviewer polls conducted recently by CNN/Time and the Elway Poll.

Elsewhere, Democrats also received encouraging news in Florida, where a new Mason-Dixon poll shows Democrat Alex Sink holding a six percentage point lead (47% to 40%) over Republican Rick Scott. That margin is slightly better than on our trend estimate, which has Sink ahead by just over three points (49.6% to 46.4%), but five of the six polls conducted in September have shown Sink with nominal leads.

Late update: A new Mason Dixon poll published this morning by the Las Vegas Review Journal shows Democratic Senator Harry Reid and Republican challenger Sharon Angle tied at 43% each. We have now seen eight remarkably consistent surveys in Nevada this month reporting margins ranging from a 3-point Reid edge to a 2 point Angle advantage. Our trend estimate gives Reid a margin of a half a percentage point (45.6% to 45.0%) -- currently the closest Senate contest in the nation.

Cross-posted to the Huffington Post

The two newest polls on New York's Senate contest out this morning come from Quinnipiac University and automated pollster SurveyUSA. Quinnipiac finds Democratic Senator Kirsten Gillibrand leading Republican challenger Joe DioGuardi by just six percentage points (48% to 42%). SurveyUSA shows an even narrower contest, with Gillibrand up by just one point (45% to 44%). Both results represent a sharp break from previous polls, which typically had Gillibrand leading by double-digit margins. Our standard trend estimate which still considers data from previous surveys, now shows Gillibrand ahead by just under eight percentage points (47.9% to 40.1%).

Both surveys also indicate a closer race for New York Governor than other polls taken previously. Quinnipiac has Democrat Andrew Cuomo leading Republican Carl Paladino by six points (49% to 43%), while Survey USA puts Cuomo ahead by nine (49% to 40%). Our trend lines show the race narrowing to a 49.0% to 37.8% Cuomo lead.

******
UPDATE: Just after we published the HuffPost version of this story, the Siena Research Institute released a new survey showing very different results from those from Quinnipiac and SurveyUSA. Their survey of all registered voters shows Gillibrand leading DioGuardi by 26 points (57% to 31%), and Cuomo leading Paladino by 33 (57% to 24%). While a likely screen would have likely produced closer margins, the differences between the Siena, Quinnipiac and SurveyUSA polls are still enormous and not easily explained.

Our updated trend estimates now show Gillibrand leading by nearly ten points (47.7% to 38.1%) and Cuomo leading by 13.5 (53.2% to 39.7%).
*****

Why the change? The most important factor is probably last week's primary elections in New York, which resolved hard-fought Republican contests for both offices. Previously divided partisans often rally to their party's nominee following a tough primary -- remember the way Barack Obama received an almost immediate boost in polls from Democrats once his battle with Hillary Clinton came to an end in 2008. So some of the change may represent a consolidation of support among Republicans. For example, DioGuardi now receives the support of 88% of Republicans on the Quinnipiac survey and 74% of Republicans on SurveyUSA's poll.

Probably just as important, both polls also represent a shift to likely voter screens. Quinnipiac's previous New York surveys have been among all registered voters, and this poll is SurveyUSA's first in New York for the 2010 cycle. Only Rasmussen had previously applied any sort of likely voter screen to the New York results -- and they also showed both races closer than other pollsters, though not quite as close as these two new surveys.

Also, while the pattern is not consistent, Quinnipiac and SurveyUSA have produced results in recent weeks that are much more favorable to Republicans than likely voter surveys by other pollsters -- in the races for Senate in Ohio and Governor in Pennsylvania for Quinnipiac, and for Senate in North Carolina for SurveyUSA. Nate Silver notes a similar pattern for SurveyUSA in House races.

The impact of likely voter screening on poll results, especially this year, is evident in the four new polls released yesterday by CNN and Time, and in three more they released last week. While their new results largely confirm what we have seen from other recent surveys, CNN and Time are somewhat unique in that they release results for both likely voters and their larger samples of all registered voters. As the table below shows, the difference on the Democrat-minus-Republican margin is often quite large -- as much as 8 or 9 percentage points in Wisconsin, Delaware, Colorado and Ohio.

It is important to remember that few likely voter screens are created equal, as different pollsters often use very different methods to model or screen for what they all describe as "likely voters." And worse, only a handful of pollsters disclose the details of their process. This is an aspect of this year's polling that we will continue to watch closely.

[Cross-posted to the Huffington Pos]

Some of you may have missed the news when it happened, and some of you may have forgotten, but we joined forces with the Huffington Post this past July (and answered some common questions about the acquisition here). Sometime later tonight or tomorrow, if all goes well, we will flip a virtual switch and begin "redirecting" traffic from Pollster.com to Pollster's new home on the Huffington Post.

A lot of very talented HuffPost developers have worked very, very hard over the last few weeks to move all of the features, content and data you have come to depend on here at Pollster to HuffPost. Our primary aim during this first wave of our relaunch has been to move everything without "breaking" anything. Thanks to the superhuman efforts of the HuffPost tech team, we think you will be satisified that while the web address will be different, everything you like about Pollster will make the trip with us.

Once we have relocated, we will begin adding some exciting new features that take Pollster.com to the next level, including quite a bit that will debut in the next few weeks. So we hope you come along and stay tuned.

Meanwhile a few more specific notes about the move:

We have managed to move every entry -- every chart, every map, every blog post, every Poll Update -- to Huffington Post. That includes our collection of charts from 2006 (which for a variety of technical reasons, I feared we might not be able to move). Needless to say, we will continue to update all active charts with new data. And your bookmarks to our existing pages should continue to work. We will simply redirect you to the new home for each page.

• Our classic format poll maps will be active and functioning and will help you scan and navigate to chart pages. These are actually already active on Pollster now for races for Senate and Governor. If you're glad to see them back, don't worry, they will remain in place on HuffPost.

• Once we move, you will also see that our charts feature prominently in a new HuffPost feature called Dashboard. We think you will find Dashboard engaging and useful -- it will include more than just polling data -- but if you prefer our classic poll maps and charts, again, don't worry, those will be there too and easily accessible via our new Pollster page.

• While we have made copies of all blog posts, the original reader comments left on those posts will remain in place on their original Pollster.com locations. The HuffPost version of each entry will include a special link to take you back to the comments left on the original Pollster.com version.

• All of our RSS feeds will continue to operate without interruption. All of our feeds will continue to provide the full post and not excerpts. Author specific feeds will require a different link, although all will be active immediately.

Now all that said, despite the best of intentions and a lot of hard work, a few things -- such as a complete index to archived blog posts -- may not be in place immediately. We will work to move anything left behind over the next week or two and will try to keep you updated on any such issues as they arise.

I welcome your comments, suggestions, problem reports or complaints -- just email me. If we have managed to "break" something you care about, please let me know. I can't promise I'll have time to respond personally to every message, but I'll definitely read them all.

A special note on comments and the Pollster.com commenter community: Admittedly, given Huffington Post's far bigger audience, the posts from me and from other contributors that also appear on HuffPost's front page will draw far more comments than our posts here. And no, we will not be migrating the Typekey user logins to Huffington Post, although you can log in and comment there using an existing Facebook, Twitter, LinkedIn, Google or Yahoo account or create an account on HuffPost.

For those concerned about the changes to the comments section, let me highlight two things. First, over the last month, Huffington Post has implemented a new "Community Pundits" feature that, as HuffPost's social news editor Adam Clark Estes explained to WebNewswer earlier this week, aims to highlight the most "insightful, informative, and engaging commentary" on any feature from across the ideological spectrum. Such comments appear in a prominent Community Pundit box that appears at the top of the comments section of each post.

Moreover, those who leave such comments consistently can earn a Community Pundit badge, which comes with privileges: "Besides having their comments highlighted in the Highlights tab and the Community Pundits box," Estes said, "we also allow our Pundits to leave longer comments."

Better yet, Estes and the Social News team have pledged to create a special Community Pundit badge specific to the Pollster section that will identify and highlight comments that are consistently insightful, informative and on topic, which is to say relevant to our focus on political polls and survey research. We have not yet begun working on this feature, so we would welcome your input and suggestions for it.

Now all that said, you should know that some entries -- especially the Outliers feature and the many "Poll Update" entries that Emily posts constantly -- will appear only on the new Pollster page and not elsewhere on Huffington Post. We're hoping that the Pollster corner of HuffPost will attract its own unique community of readers, so we encourage those of you who comment frequently to come along and try it out. We hope that the existing community can move along with the charts and the blog archive.

If you have questions about Huffington Posts comments and moderation policies, please see this FAQ page.

Within a few hours of my update yesterday, which highlighted a new Rasmussen survey in West Virginia showing Democrat Joe Manchin leading Republican John Raese by seven percentage points (50% to 43%), Public Policy Polling (PPP) released another automated survey there showing the Democrat trailing by 3 (43% to 46%). Whether you prefer our trend estimate or a simple average of the two surveys, the bottom line is the same: On the basis of these two recent polls, the race merits "toss-up" status.

In Wisconsin, a new PPP survey paints a picture that even the survey sponsor Daily Kos characterized as "uber-ugly" for the Democrats. It shows Democratic Senator Russ Feingold trailing Republican Ron Johnson by eleven points (52% to 41%), a slightly larger margin than measured by a Rasmussen automated survey a week ago (51% to 44%). Our trend estimate splits the difference these two results, the only two public polls released in Wisconsin so far in September, pushing the state into our "lean Republican" classification.

Democrats pushed back yesterday, sharing with TPM results on an internal poll conducted before last week's primary showing "Feingold ahead, by 48%-41% among all voters and 47%-43% among those definite to vote."

Incidentally, one reader took me to task last week, appropriately, for not noting PPP's status as a firm that polls for local Democrat candidates (though they have not disclosed doing work for candidates for U.S. Senate and Governor). That said, their results in West Virginia and Wisconsin tend to counter the notion that the Democratic firm produces results biased toward the Democrats.

A batch of new automated surveys released yesterday by Rasmussen Reports and their subsidiary Pulse Opinion Research (for Fox News) generally confirm other polling in the Senate races in California, Ohio, Pennsylvania, Nevada and New York.

The new Fox/Pulse survey in Nevada has Republican Sharon Angle up by a single, non-significant percentage point (46% to 45%), generally confirming what other recent polls suggest is a slight tightening in the race. Our standard trend estimate, which gives greater weight to the surveys conducted earlier in the month, shows Reid leading by a single percentage point (46.3% to 45.3%). Our more sensitive estimate (shown below), which gives greater weight to the most recent surveys, has it dead even (44.9% to 44.9%).

In Alaska, Rasmussen was first out of the box with a poll testing a three-way race with incumbent Senator Lisa Murkowski running as a write-in candidate. They show Republican nominee Joe Miller with 42%, Murkowski with 27% and Democrat Scott McAdams with 25% of likely voters. While the Rasmussen release did not include the specific language of their vote preference question, they did provide this curious description:

Polling for write-in campaigns is always challenging, so results should be interpreted with caution. For this survey, Rasmussen Reports asked respondents about a choice between Miller and McAdams without mentioning Murkowski. That is the choice voters will see when they enter the voting booth. However, when response options were offered to survey respondents, Murkowski's name was mentioned.

They only provided results for a three-way contest, so this reference must be to the structure of their question. Presumably, they first mentioned that Miller and McAdams were the names on the ballot, then offered Miller, McAdams and Murkowski as choices. For more on how pollsters will measure vote preference in Alaska, see my Monday update.

California's race for Governor provided yesterday's ray of hope for Democrats, where a new PPP poll showed Democrat Jerry Brown leading Republican Meg Whitman by five points (47% to 42%) while a new Fox/Pulse survey has the race dead even (at 45% for each). Those results are a slight improvement over five other surveys conducted in late August and early September by Rasmussen, Pulse, SurveyUSA and CNN/Time.

Our standard trend estimate, which gives greater weight to the earlier surveys, shows Whitman leading by just under three points (47.1% to 44.2%). Our more sensitive estimate, which gives greater weight to this week's polls puts Whitman ahead by slightly less than two (47.0% to 45.1%). Either way, the polling puts the California Governor's race in our toss-up category.

And this just in: Quinnipiac University released two new polls early this morning, including a eyebrow raising result in the New York Governor's race where they show Democrat Andrew Cuomo leading Republican Carl Paladino by just six percentage points (49% to 43%). Previous surveys conducted over the summer had shown Cuomo leading Paladino by 30 or more percentage points.

In Pennsylvania's Senate race Quinnipiac shows Republican Pat Toomey leading Democrat Joe Sestak by seven percentage points (50% to 43%), roughly the same margin as our previous trend estimate.

Cross-posted at the Huffington Post