3 takeaways from the most authoritative autopsy of the 2024 election yet

It’s been more than six months, but Democrats are still picking over the cold, dead body of the 2024 election. The latest autopsy comes courtesy of Catalist, a Democratic data firm with a widely coveted voter database.

By now, you may feel that you know more about how Democrats lost last year than you ever wished to know. Which would be understandable. But Catalist’s findings are especially authoritative, as the firm tracks the actual voting behavior of 256 million Americans across all 50 states and the District of Columbia. In other words, they are not relying purely on surveys of how people said they would vote, but also hard data showing which party individual voters registered with, and which elections they did and did not show up for.

Previously, David Shor of Blue Rose Research released a 2024 analysis that drew partly on similar data sources. But Catalist boasts the longest-running voter database of any institution besides the Democratic and Republican Parties, as it has tracked the electorate’s behavior for over 15 years. Many, therefore, consider its characterizations of shifts in voting patterns to be uniquely trustworthy.

Their entire report is worth reading. But I’d like to spotlight three takeaways that have especially significant implications for Democratic strategy going forward.

(One note: When Catalist reports election results, it strips out all ballots cast for a third party. This is because the third-party share of the vote is highly noisy from one election cycle to another, shifting in response to semi-random factors, like whether a rich businessman decides to throw his hat in the ring. Thus, all the figures cited below represent the Democratic Party’s share of all ballots cast for a major party presidential candidate in a given election year, not its share of all votes cast, although the two tend to be very similar.)

Some analysts have attributed Harris’s loss entirely to weak Democratic turnout. Michael Podhorzer, a former political director of the AFL-CIO, argues that American voters didn’t shift “rightward” in 2024 so much as “couchward.” In his telling, Trump didn’t prevail because he won over a decisive share of swing voters, but because Democrats failed to mobilize America’s anti-MAGA majority.

And many on the left attribute that failure to Harris’s centrism: Had she not taken her party’s base “for granted,” she could have ridden high Democratic turnout to victory.

The evidence for this view has always been weak. But Catalist’s data makes its falsity especially clear.

Drawing on voter file data, the firm found that 126 million Americans cast a ballot in both the 2020 and 2024 elections, a group it dubs “repeat voters.” And Catalist determined how these Americans voted in each election. This is the exact data necessary for resolving the debate over whether Trump won over swing voters. Looking at raw election results, it’s hard to tell whether a decline in Democratic support was derived from the same voters switching sides or different people showing up at the ballot box.

But here, Catalist provides us with a large, fixed voter pool. Any drop in Democratic vote-share among these 126 million individuals could only come from Biden 2020 voters flipping to Trump. And the data shows that Biden won 51.6 percent of repeat voters in 2020, while Harris won only 49.4 percent of them last year.

Meanwhile, there were 26 million “new voters” in 2024, which is to say, voters who hadn’t cast a ballot in 2020. Democrats have historically won new voters by comfortable margins, largely because young Americans were overwhelmingly left-leaning in 2008, 2012, 2016, and 2020. But last year, Trump won new voters by about 3 points.

One could attribute this development to either turnout or persuasion. Some voters who didn’t cast a ballot in 2020 — either because they were too young or too disengaged that year — strongly prefer one party over the other. So maybe Trump mobilized lots of previously inactive voters who always favored the Republican Party, while Harris failed to energize enough of those who always preferred the Democrats.

On the other hand, it’s possible that Republicans won over many young or disengaged voters who had previously lacked a strong partisan attachment or had favored the Democratic Party.

In reality, both these factors were likely operative. Indeed, it is extremely improbable that Democrats’ difficulties with new voters were entirely attributable to turnout. Some young and irregular voters just started tuning into politics and forming a partisan preference over the past four years. And survey data indicates that Republicans converted many such voters to their cause.

All this said, Democrats surely saw weaker turnout than Republicans last year, and this was partly responsible for Harris’s loss. According to Catalist, 30 million Americans voted in 2020 but not in 2024. And this group of “dropoff” voters had supported Biden over Trump by a 55.7 to 44.3 percent margin four years ago.

We can’t safely assume that this bloc would have voted for Harris over Trump by similar margins. In fact, it is likely that this population became more sympathetic to Trump over the past four years. Unreliable voters tend to have weaker partisan identities, and the decision to sit out an election often reflects a voter’s ambivalence about which candidate they prefer. Nevertheless, if every 2020 voter turned out last year, Harris would almost certainly have done better.

Democrats do need to try to mobilize their coalition’s most unreliable members. They just can’t do so at the expense of winning over swing voters.

Fortunately, there is not necessarily a stark tradeoff between these two tasks. Biden-supporting “dropoff voters” were not typically hardline progressives outraged about Biden’s complicity in Israeli war crimes or Harris’s courting of NeverTrump conservatives. Rather, such unreliable Democratic leaners tend to be politically disengaged and ideologically heterodox, much like many swing voters. According to Catalist’s modeling, the lower a Democratic-leaning voter’s propensity to turnout for elections, the more likely they are to consider voting for a Republican.

Like AP Votecast and Blue Rose Research, Catalist finds that younger voters were significantly more Republican in 2024 than they had been in 2020. While Biden won 61 percent of voters under 30 four years ago, Harris won only 55 percent of that demographic last year (notably, this is a smaller decline than Blue Rose Research registered).

This decline was driven almost entirely by the rightward drift of young men. Harris won 63 percent of women under 30, just three points lower than Biden in 2020. But she won only 46 percent of men under 30, which was nine points worse than Biden’s showing.

Harris actually won the same share of the white vote that Barack Obama had in 2012. And her support among America’s white majority was only 2 points lower than Biden’s in 2020.

But like previous 2024 autopsies, Catalist’s report finds that Democrats suffered steeper losses with nonwhite voters, particularly those who were young, male, and/or politically disengaged.

Harris won 85 percent of Black voters, down from Biden’s 89 percent. That drop was entirely due to flagging support from Black men, as this chart shows:

Democrats suffered especially large losses with young Black men, winning only 75 percent of their ballots in 2024, compared to 85 percent four years earlier.

The trends among Latino voters were similar. Between 2020 and 2024, Latino support for the Democratic nominee dropped from 63 to 54 percent (as recently as 2016, Democrats had won 70 percent of the demographic). The decline among Latino men was particularly pronounced, as Trump won a 53-percent majority of that historically Democratic constituency:

Democratic support among young Latino men fell off a cliff. And the party lost even more ground with Latino men under 30 who vote irregularly — which is to say, those who missed at least one of the last four general elections in which they were eligible to cast a ballot.

Finally, Harris won only 61 percent of Asian American and Pacific Islander (AAPI) voters. Back in 2012, this group had backed Obama over Romney by a 74 to 26 percent margin. As with other nonwhite voting blocs, AAPI men are leaving the Democratic coalition faster than their female counterparts.

Taken together, all these figures paint a disconcerting picture for Democrats. The party has long wagered that time was on its side: Since America’s rising generations were heavily left-leaning — and the country was becoming more diverse by the year — it would become gradually easier for Democrats to assemble national majorities, even as the party bled support among non-college-educated white voters.

And it’s true that Democrats still do better with young and nonwhite voters than with Americans as a whole. But the party’s advantage with those constituencies has been narrowing rapidly. Last year’s returns suggest that demographic churn isn’t quite the boon that many Democrats had hoped, and can be easily outweighed by other factors.

Meanwhile, as blue states bleed population to red ones, Democrats are poised to have a much harder time winning Electoral College majorities after the 2030 census. Given current trends, by 2032, a Democratic nominee who won every blue state — and added Michigan, Wisconsin, and Pennsylvania — would still lose the White House.

How Democrats can arrest the rightward drift of young and nonwhite Americans — while broadening their geographic base of support — is up for debate. But pretending that the swing electorate does not exist, or that unreliable Democratic voters are all doctrinaire progressives, probably won’t help.