Articles and Analysis


Late Deciders in Recent Presidential Elections

On October 1st I noted that we weren't likely to see much movement in the polls in October. This was based on survey data from the past two campaigns that indicated that few voters tend to change their minds once they have settled on a candidate. Of course, if an October comeback was fairly unlikely, then a final week comeback is undoubtedly a longer shot.

According to this site's national trend estimate, Obama's margin is almost twice as large as the percentage of undecided voters left. Thus, at this point, McCain's only path to victory involves attracting support from voters who are currently planning to vote for Obama. This certainly isn't impossible. After all, pre-election polls ask voters which candidate they would vote for if the election were held today. Just because a respondent says they would vote for a particular candidate if the election were held today does not necessarily mean they have made a final decision on that candidate. For example, the ABC News/Washington Post tracking poll indicates that 9% of respondents who have chosen a candidate say that there is a chance they could change their minds. Should this give the McCain campaign any hope?

To answer this question, I looked at exit polls from the last four presidential contests. In each year, the exit polls included a question asking respondents: "When did you finally decide who to vote for in the presidential election?" This question provides a way of capturing which voters had not completely settled on their vote choice until the last week of the campaign. The chart below plots the percentage of late deciders across the past four presidential elections.


Interestingly, voters appear to be settling on their vote choices earlier in recent campaigns. In 1992, one-quarter of the electorate said that they did not come to a final decision until the final week of the campaign and the figure was about 30% in 1996. However, by 2004, nearly nine in ten voters reported that they had settled on their presidential vote choice before the final week of the campaign. Whether it is because of increasingly longer campaigns or heightened polarization, the fact that voters are making their final decisions earlier in recent contests does not bode well for the McCain campaign. In short, there are fewer late deciders to win over than there were in previous years.

Nevertheless, according to the ABC News/Washington Post survey, 8% of Obama supporters say that they could still change their minds (11% of McCain supporters say the same). Is there a chance that McCain can win over those Obama supporters that still have doubts while holding on to his own soft support? Recent history suggests that such an outcome is unlikely. The chart below breaks down the vote choices made by those who said that they came to a final decision during the last week of the campaign.


According to the evidence from the exit polls, in every election since 1992 Democrats have fared better than Republicans among late deciders. Of course, it may be the case that in these elections Democratic support was softer than Republican support going into the final week. But in none of the last four elections did late deciders break more for the Republican candidate than for the Democrat. Once again, this pattern does not give the McCain campaign much hope.

Overall, current polling and recent history suggests that there is little hope for a final week comeback. There are fewer late deciders in recent elections than there have been in the past, a pattern that seems to be holding in this contest. Furthermore, late deciders have tended to break more for the Democratic candidate in previous elections, not the Republican. Thus, the prospect of a McCain comeback seemed quite unlikely at the beginning of October and it appears to be truly improbable now.



I don't know about you but I feel better.



Well, it is nice to see nubers when the problem is Human. If we could be graphed and calculated many campaigns would have an advantage. Fortunately we are not. We change our minds at a moments notice. We have a change of heart by outside influences, and we are prone to peer pressures.

Does Obama win? many, like me, hope so. The problem is we are relying on human nature. I will not believe Barack Obama wins untill the morning of November 5th.



Great analysis. I have heard many pundits (most notably NBC's Chuck Todd) say repeatedly in recent weeks how the undecideds will likely break overwhelmingly for McCain. That was just counterintuitive for me, but I had no evidence to disagree. My take on it is that these late deciders would tend to fit a Democratic profile more than a Republican profile. At best, I would say the undecideds might break 50/50 in this election.


Joseph Marshall:

One pattern I have noticed in the National graph is whether or not the tracks between the two candidates turn roughly parallel or diverge in opposite directions. One of the most striking things is the sharp divergence between the tracks from John McCain's high water mark of 48 on or about September 9. What you see from then until October 12 is both a steep rise in Obama's figures to 50% as well as a sharp drop in McCain's to 42%.

The polling history as a whole clearly shows that the 42% figure represents the impenetrable bottom of McCain's base, and Obama gained a full 3 points over his previous high figure. For the last two weeks, the tracks have been roughly parallel with today's graph showing an eight point spread and 6.5 spread of undecided.

Dr. Sam Wang over at PEC has an interesting article about "undecided" voters often having a subthreshold or latent decision already made.

It strikes me that this is what we are seeing in the national graph, and, that could we measure the latent decision, there would actually be an 8% bias in the "undecided" pool toward Obama that will reflect in a final result of 55.7% Obama and 44.3 for McCain.


If this does happen, one could argue the possibility that the weekend of Oct. 11-12 was when the election finally was over in the minds of the voters, whether they knew it or not.



I'm going to have to play devil's advocate.

1. Simply extrapolating from a very limited trend in old data doesn't establish a very firm argument for what will happen in 2008. Otherwise one might have predicted just prior to the 2000 election that last-week deciders would go up by citing the 1992-1996 trend - and that would have been wrong.

2. The smallest number you cite, 11%, is still a hefty sum - more than enough to change the outcome in most battleground states. You could even make a fair case that when evaluating undecided behavior it is most appropriate to compare with other years in which neither candidate was the incumbent. For 1992 and 2000 your figures are 25% and 18%, respectively.

3. Dr. Franklin provided detailed charts on this site several weeks ago showing that this year's undecided pool is tracking the 2000 pattern closely and is substantially larger than in 2004.

4. Finally, in that same post, Dr. Franklin also graphed poll averages for the 2000 and 2004 elections, including last-week results and the penultimate poll - the election results themselves. If you step back just a few days and look at where polls stood going into the final weekend you can see that in both years there was a final weekend movement towards the incumbent party's candidate and this movement was a reversal of the general trend of the prior month.

This is consistent with what Chuck Todd and many others say about the extremely late deciders. They are a cautious bunch and when forced to choose are more likely to go with the least change, the most familiar, i.e. the incumbent party.

Now Dr. Franklin's data only looks at two prior elections, so it's not going to provide any rock solid predictions either. Still, I would expect to see national polls tighten somewhat during the last few days. Dr. Franklin's data would suggest that any state that's still a toss-up going into the final weekend would favor McCain on Nov. 4, despite the overall trend towards Obama over the prior month. I suspect that this will be particularly likely in states in which the traditional comfort-zone party has been Republican.

That being said, I hope I'm completely wrong.


There are a few very large, unacknowledged elephants that are sitting in on the polling discussions.

1) The 'RCP average' of all polls is flawed. Obama's lead nationally is between 4 and 5 points, not 7-8.

2) All polls publicly listed now expect a higher Democratic turnout than has been since the 30's. This is a guess and, with party affiliated polled people voting 8-1 for their party's candidate, it's a guess that significantly impacts the poll result. And its not a scientific guess. Turnout projections are famously wrong. Just check the democratic primary this year. If voting this year is 2% higher Democrat this year than 2004, this is essentially an even race. Current polling projections give Dems a 6-7% advantage.

3) Obama needs to be ahead by 5-6 points in the national polls to be ahead in the battlegrounds. This is because of his intense support in the coastal blue states. By this I mean the battlegrounds as a whole. And Obama does not need to win all the battlegrounds to win the Elec college. But make no mistake, these states are very tight.

4) Obama is African American and no African American in a significant race in the past several decades has out-performed his or her final pre-election poll numbers. Republican or Democrat. Win or lose. However, this year may be different.

This race is very, very tight with Virgina being the key state unless McCain picks of Pa.


I would like to clarify that I think a 'safe' final lead for Obama in an average of all national daily tracking polls (the pros, not the outliers) is in the 5-6 range. Below that, I think OH, MO, Fla, NC, NV, Col and even Iowa are all at risk. Remember that Obama leads NY, Ill, and California by over 25 points. This is a very large popular vote bubble that means nothing in the electoral equation.



hello all,
I am lost and I was hoping you will be able to clear things up for me. I will start by admitting that I am leaning Mcain. But I do respect each individuals right to hold their own opinion. I respect those who tell me that they are voting obama and have a concrete understanding of why. Most of the responses I have gotten are "he's black", "i'm a democrat and thats all i'll vote", so far that is probably the extent of an credible explanations for voting for obama. but I respect them, at least they are honest.
Where I am completely baffled is how so many "americans" can stand behind a candidate that is a tried and true marxist, and not even trying to hide it, who's every relationship from his past has been with "american hating socialists", who believes the constitution is "outdated", and every speech this man has EVER given has came straight from the pages of sol olenski's "rules for radicals". If the main street media had actually done their job, obama would have been run out of town by means of pitchforks before the primaries were over, and I do believe that history will show that 2008 was the year "journalism" died in america.
Yet this phenomenon just continues to amaze me. So many americans are so caught up in the montras and bumper sticker slogans, that they are not even bothering to look at character, substance, experience, or leadership abilities.
Can anyone explain to me this "I am willing to be blindly led around by the nose" mentality that has seemed to grasp our country by the throat. This wonderful country that I was willing to serve in our military for 6 years to protect. Where has the United States of Ameica gone? I really don't want to live in the United Socialistic States of America.


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