These data show that over the course of the campaign, Clintons percentage of Democrats has declined from 84 to 76, while Trumps share of Republicans has increased from 68 to 76.
Moreover, Trump has twice as many Democrats (6 percent) as Clinton has Republicans (3 percent), and she is no longer winning Independents. The good news for her is that the gap between Democrats and Republicans is now larger than in 2012.
Breaking the party variable down, Clintons problem is not with strong Democrats but, rather, with those who classify themselves as weak Democrats or leaning Democratic.
Going into the last eight weeks of this campaign, the biggest anomaly is the number of voters who claim to be either voting for a third party, are not going to vote, or are undecided.
In January of 2016, we started tracking these people closely. From then until early June, when the major party nominees emerged, that number held steady at about 20 percent. Once it was clear that the choice was between Trump and Clinton, the number jumped. In May, 19 percent of respondents said they werent either Trump or Clinton backers. In June, the percentage climbed to 24 and in July and August, it zoomed up to 31 percent. These disaffected Americans were evenly divided between those who said they were voting third party, those who were undecided between Trump and Clinton, and those who vow to sit this one out.
Given recent electoral experience, this is a very large number. In August of 2012, by way of contrast, the best estimate among experts quoted in the New York Times was that the actual share of voters who are up for grabs is probably between just 3 percent and 5 percent.