Articles and Analysis


The Changing Partisan Landscape in Key States

One factor that pollsters must deal with is a dynamic electorate. While these changes can be significant at the national level, they may be even more pronounced within particular states. Indeed, we have heard a great deal about the large numbers of citizens that Democrats have registered over the past few years. But how big a difference has this really made? To get a sense of this, I gathered party registration data for seven swing states. The chart below compares the percentage of citizens registering as Democrats and Republicans in 2008 to the same figures in November, 2004 (obtained from the Secretary of State websites).


First, a disclaimer. Party registration is not necessarily comparable across states. For example, New Hampshire's open primary law allows independents to vote in either party's primary while North Carolina's Pennsylvania's closed primary rule means that you must register with a party to vote in that party's primary. Thus, the incentive to register with a party is greater in North Carolina Pennsylvania than it is in New Hampshire (which is why North Carolina's Pennsylvania's figures are higher than in New Hampshire).

Nevertheless, the change (or stability) within each state provides important information and, in most cases, this information appears to favor Democrats. In percentage terms, Republican registration has declined in six of the seven swing states since 2004 (New Hampshire is the exception) while Democratic registration has increased in four of the seven states. Not every state has seen significant partisan changes. The partisan balance in Florida, New Mexico, and North Carolina is quite similar to what it was four years ago. But in four other states, the changes are more significant.

In two states that went for Kerry in 2004 (New Hampshire and Pennsylvania), Democrats have improved their standing among registered voters. In Pennsylvania, a state that the McCain campaign is still targeting, Democrats held a 7% advantage in party registration in 2004 compared to a 12% edge now. Democrats have also made big gains in two states that went for Bush in 2004--Colorado and Nevada. In Colorado, Democrats have cut the Republican registration advantage in half since 2004, from 6% to 3%. But Nevada provides the most stunning example of partisan change. In 2004, Republicans held a 1% edge in party registration; however, just four years later, Democrats now hold a 6% advantage.

These registration figures point to the difficulty that McCain faces in trying to pick up states like Pennsylvania and New Hampshire. Those states went for Kerry four years ago and have only become more Democratic since. The party registration statistics also indicate why Colorado and Nevada have become such good targets for the Obama campaign. In both states, Democrats have made dramatic gains.

What does all this mean for polling? We don't know for sure, but these dynamics do suggest some questions we should be aware of. For example, will these newly registered voters be included in pollsters' likely voter screens? Will those who are newly registered actually turn out on election day? Are all survey firms accounting for these trends when applying partisan (and demographic) weights to their samples? And--the key question--what will the changing partisan landscape in these states mean on election day?

NOTE: See the raw registration numbers here: View image

Unfortunately, states like Michigan and Virginia do not have partisan registration so a similar analysis is not possible in those swing states.

UPDATE: A reader pointed out that in my original post, I mistakenly stated that North Carolina has a closed primary, which is not true. In fact, North Carolina does allow unaffiliated voters to vote in party primaries as long as the parties themselves agree. Both parties have agreed to do this in recent election cycles, so North Carolina has had semi-open primaries in recent years. The states that I've looked at here that have closed primaries include Florida, Nevada, New Mexico, and Pennsylvania.



And so.. to what extent are pollsters accounting for this w/state polls?

which pollsters take the state's dem/rep changing distribution into acct when weighting data?



I find it frightening that in states like Florida where there are 260,000 more registered Democrats than Republicans that Obama is not ahead in the polls. Is it possible that the polls are not reaching many of the working class Democrats?



Also students are notorious for not having home phones to poll to. I think if the pollsters had cell phone numbers of registered voters you would see a much more Democratic looking electoral map.



Pollsters are also reaching the most conservative sector of americans who are at home answering their home phones. I really don't think it is as close as the polls have it.



For what it's worth, I read somewhere many weeks ago that the media want this to be a close race - it's good for ratings and advertising income. Could that be a reason that we are being led to believe that the race is closer than it is? I hope so.



I just thought of this. I don't know why it didn't occur to me sooner. Some states, PA for example, have a glaring difference in party affiliation, 12% Dem advantage in that case. If Rasmussen is using a weighted filter, now 5% Dem advantage over the Reps because that is the national avg. doesn't that short change the Dems by a large amount? And likewise in a red state like Utah, are they still using the filter assuming a 5% Dem advantage over the Reps.

If this is true it is a HUGE blunder in methodology!



I wonder about the effect of some newer phone technologies. I use Caller ID and I won't answer the phone if I don't recognize the caller. I let it go to the answering machine instead and wait for a message. No message, no answer.
Do the pollsters have a policy that deals with this? I suspect that they just hang up when they get the answering machine or voice mail and move on to the next target. Does anyone know more about this?


Dr. Mundon:

bearman, I think one of the reasons why Obama may not be showing up in polls where Dems seem to have an edge is the lag pollers may have in updating their algorithms for weighting the poll results. Every poll taken that you see doesn't just publish raw results; they weight the results using assumptions about the "actual" demographic distibution of the electorate. For example, if a pollster asked 1000 people in a state whether they were supporting Obama or McCain, and the pollster got 500 for Obama and 500 for McCain, AND the pollster believed that in the state 60% were democrats and 40% were republicans, they would publish a poll with a result not of %50/50, but something weighted more in the direction of %60/40, to account for this "bias". A good discussion of this and other elements of polling can be found on electoral-vote.com, under the polling FAQ :




I think one thing pollsters often fail to beware of is the danger of weighting polls by registration. Registration is often a very distorted mirror of actual voting behavior in a state.

Where I'm from, PA, there is an overwhelming Dem reg advantage but as we've seen in the past two elections things are much tighter.

Obama's strength in PA will come from Philadelphia and the suburban Philly counties. These suburban counties have an overwhelmingly Republican reg but most of them having been going D for President since the 90's.

Conversely in the Western half of the state the counties surrounding Pittsburgh have a huge Democratic registration advantage, but have one by one slipped into the R column in Presidential elections.

Its a political realignment in progress based on a Philly liberal suburbanite vs. Western PA Bitter guns and God type thing.

So its dangerous (at least here in PA) to weight by registration. Much better to weight it by some type of actual voter performance number.


Post a comment

Please be patient while your comment posts - sometimes it takes a minute or two. To check your comment, please wait 60 seconds and click your browser's refresh button. Note that comments with three or more hyperlinks will be held for approval.