How Democratic Senators Survived the Trump Tide

Did an undervote save battleground Democrats?

November 5th was almost much, much worse for Democrats. Amidst news of a GOP trifecta and the nominations of Gabbard, Kennedy, and Co., a worse scenario for Democrats is hard to imagine. But if not for strong performances from battleground Senate candidates, Democrats would be staring down the barrel of a nearly filibuster-proof Republican majority in the Senate. 

Four Democrats—Elissa Slotkin, Tammy Baldwin, Jacky Rosen, and Ruben Gallego—won in states that Trump flipped from blue to red. Such a feat defies recent political history. When a presidential candidate flips a state, their party almost always wins the concurrent Senate race. For example, Democrats won all Senate races in states that Biden flipped blue in 2020. Republicans did the same in 2016. In fact, between 2004 and 2020 such split outcomes have happened just twice—Democrat Joe Donnelly’s 2012 win in Indiana and Republican Judd Gregg’s 2004 victory in New Hampshire.  

Had the GOP conformed with precedent this year—an entirely reasonable outcome given Trump’s strong performance—they’d start the next Congress with 57 Senate seats. Not to mention the handful of very winnable seats that Republicans missed two years ago! Imagine stronger candidates in place of Blake Masters, Dr. Oz, and Herschel Walker—all of a sudden Democrats are down to 40 seats. 

So, to Democrats desperate for a piece of good news: Entering the 2026 cycle with 47 Senate seats is a small miracle. 

How did Democrats eke out Senate wins in states that Trump flipped? Each certainly benefited from ticket-splitting. But Democratic success may also owe to the traditional “undervote”—voters who selected Trump and left the rest of their ballot blank. Others, meanwhile, voted for a minor third-party Senate candidate, effectively the same as an undervote. 

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In the table above, the Michigan and Nevada races immediately stand out. Slotkin and Rosen both won despite receiving fewer votes than Harris—who lost both states. This phenomenon—the winning Senate candidate receiving fewer votes than the losing presidential candidate—had happened just twice this century (Minnesota ‘08 and Nevada ‘12). The 2024 elections doubled that tally. 

Overall, as Kyle Kondik notes, the national undervote was actually inline with past elections. But with so many close Senate races in presidential battlegrounds, every undervote mattered more. If Nevada’s Sam Brown and Michigan’s Mike Rogers had come just a bit closer to Trump’s vote total (or even Harris’s!), they would be in DC for Senate orientation. Let’s take a closer look at both of those races. 

In Michigan, Mike Rogers’ vote total of 2.69 million was 95.6 percent of Trump’s, while Slotkin’s 2.71 million was 99.1 percent of Harris’s. Unsurprisingly, then, Rogers received more votes than Trump in only one spot: Leelanau County—a left-trending area in Northwest Michigan that still votes GOP down ballot. 

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More interesting are the counties where Rogers’ vote total lagged further behind Trump—the darker counties on the map above. Aside from a strange underperformance in Bay and Arenac counties, Rogers’ total ran behind Trump the most in Genesee and Wayne counties, home to Flint and Detroit, respectively. 

As Trump gained ground with Michigan’s non-white voters, both counties swung substantially to the right at the presidential level. But Rogers’ lower total suggests these converts are not yet voting for Republicans besides Trump. Many voted for Slotkin and House Democrats—or simply didn’t vote for anyone else at all. 

A Trump undervote is even more recognizable in Nevada. Though Rosen outran Harris in every county, her improved margins were most notable in the rural areas beyond Vegas and Reno—where she managed to lose by less than Harris did. The table below breaks down four of these sparsely populated counties. 

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Though Rosen beat Harris’s margin by between 6 and 11 points, her vote share really isn’t all that much higher. Rosen’s rural strength hinged on Sam Brown dramatically underperforming Trump’s vote share, often by 7+ points. 

In the Nevada presidential race, third parties and the “none of these candidates” option did not exceed 2.7 percent anywhere. In the Senate race, meanwhile, the share exceeded 5.5 percent in every single county—and was often closer to 10 percent. This sizable “other” vote almost certainly cost Brown thousands of votes. 

Many Nevadans headed to the polls, cast a ballot for Trump, and then selected a third-party or “none of these candidates.” Interestingly, this type of vote appears disproportionately concentrated in the ruby-red rural areas. This suggests the “Trump alone” segment of the electorate extends to rural, white voters as well—not just the non-white populations we saw in Michigan. 

One possible explanation in Nevada? The Rosen campaign’s heavy spending advantage allowed Democrats to negatively define Brown before he was on air. As a result, voters who might have gone straight-ticket GOP ditched Brown, but couldn’t quite bring themselves to vote for a Democrat—so they selected a third option or left the Senate race blank. 

The undervote, of course, is difficult to disentangle from persuasion effects. It’s easy to rattle off other factors that contributed to Democrats’ Senate success. But this was still a historically remarkable performance. And, at the margins, a Trump undervote might have made all the difference. 

This will be a crucial factor as we turn towards 2026: What share of Trump-only voters will show up in the midterms? Can the GOP retain their first-time non-white voters? Realignment—or not—hangs in the balance.