Presidential general elections are generally determined by two factors: the size and relative enthusiasm of each major party’s base, and which way the swing voters in the middle go. Every four years, members of both parties debate which factor is more important—turning out their partisans or appealing to the middle. The reality is that parties are like people: They should be able to walk and chew gum at the same time.

The Democratic base is slightly larger than the Republican base and, at least since President Trump took office, Democrats have had an intensity advantage of varying degrees over the GOP. These combine to give Democrats a slight edge in terms of winning the national popular vote, but not necessarily the 270 Electoral College votes needed for victory, as they painfully learned in 2016.

Yet it’s worth noting that in the last three elections, independents have gone against the party holding the White House.

To take a closer look at those pivotal voters in the middle, The Cook Political Report collaborated with the nonpartisan Kaiser Family Foundation to analyze swing voters, combining the samples of Kaiser’s May 30-June 4 and July 18-23 national health tracking polls to get a robust sample of swing voters for closer analysis. Kaiser conducts tracking polls roughly 10 times a year, with a particular focus on health-related issues. The two surveys interviewed 2,402 adults (2,030 registered voters), reached on both landlines and cell phones by live interviewers. This is double the size of the normal individual national polls we see, with a margin of error of plus or minus 3 percentage points.

Voters were asked whether they would definitely or probably vote for President Trump next year, or definitely or probably vote for the Democratic candidate. Among all registered voters, 29 percent said they would definitely vote for Trump, 9 percent said they would probably vote for him, 13 percent said they would probably vote for the Democrat, and 34 percent would definitely side with the Democrat. That gives Democrats a 47 to 38 percent advantage. Eight percent were undecided, and 7 percent either refused to answer or said they would vote for someone else.

Thirty percent of the respondents, a total of 603, can be called swing voters, who were either undecided or only “probably” going to vote for either Trump or the Democrat. Of the 9 percent who said they would probably vote for Trump, just over half (5 percent of all voters) said there was a chance they would vote for the Democrat, while 4 percent said no chance. Of the 13 percent who would probably vote for the Democrat, just a quarter (3 percent of all voters) said that there was a chance they would vote for Trump, while the others said there was no chance. Those who only probably would vote for one candidate but definitely would not vote for the other have a good chance of either not voting or throwing a vote to a third-party candidate.

But who are these swing voters? What makes them different from those who have decided, and from the overall electorate? Swing voters tend to be younger, more moderate, and less engaged in politics compared to those who have decided and to the overall electorate. While 72 percent of voters who are 65 years of age or older have decided for sure, just 47 percent of 18-29-year-olds have decided.

Ideologically speaking, 56 percent of all swing voters identify themselves as moderates, compared to 38 percent of all voters. Just 16 percent of swing voters called themselves liberal, while 26 percent self-identified as conservative. Eleven percent of all voters are “pure independents”—that is, they don’t identify with or even lean toward either major party—but 18 percent of swing voters are pure independents.

When asked, “How much attention do you normally pay to what is going on in national government and politics?” 57 percent of voters and 68 percent of decided voters said they pay a lot of attention, but only 39 percent of swing voters said so. Twice as many swing voters said they pay only a little attention or none at all—17 percent, compared with just 8 percent of those who are decided.

Not surprisingly, fewer swing voters believe it is important who wins. When asked whether it really matters who wins, somewhat matters, or doesn’t really matter, 82 percent of all voters and 92 percent of decided voters said they believe it matters, but just 66 percent of swing voters said they believe it really matters.

Finally, when swing voters were asked to think exclusively about several individual issues and whether each made them more or less likely to vote for Trump or the Democrat, Democrats had the advantage among swing voters on climate change (net +38), health care (+18), and immigration (+10), while the issue of the economy (+12) gave Trump an advantage.

The key takeaway from this analysis is that while swing voters don’t look too different from the overall electorate in terms of demographics, they are very different temperamentally. Since they pay less attention than other voters and are less likely to believe that the outcome is important, you just have to wonder how many of these undecided will really vote. Further, we can expect those who do to check into the race very late.

This story was originally published on on September 6, 2019

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