What the special election in Tennessee's Seventh District means for the 2026 midterms

Republicans held a Trump +22 seat — but by only 9 points. A swing half as large would give Democrats the U.S. House in 2026, and put the Senate clearly in play

Voters in Tennessee’s 7th Congressional District voted on Tuesday, Dec. 2, to fill a vacancy left by Republican representative Mark Green, who resigned from Congress in July 2025. The election for this rural seat went for Republican candidate Matt Van Epps over Democratic candidate Aftyn Behn, with Van Epps having a 9-point margin in the vote as of 10:30 PM ET on Dec. 2. Some ballots are still being counted.

While Republicans held the seat, Van Epps’ 9-point margin is a significant shift to the left since 2024. Green won the seat by 21 points in 2024, and Donald Trump carried it by 22 points over Kamala Harris. Behn’s 9-point loss is a 13-point shift toward Democrats in a little under a year. The fact that a rural Tennessee district ended up just a high-single-digits win for Republicans should be a five-alarm fire for the party ahead of the 2026 midterms.

Specials keep pointing to a big Dem. win in 2026

Zooming out, the election on Tuesday confirms a broader trend in recent special elections to vacant congressional seats. Democratic candidates in special elections have been dramatically outperforming benchmarks based on the 2024 election. The result in TN-7 is 13 points less Republican than in 2024, in line with other congressional specials that have an average 17-point swing. And it is higher than other down-ballot special elections: Specials for state legislative seats have moved to the left at more like an 11-point clip in 2025.

For context, in the 2018 midterm cycle, Democrats beat their benchmarks in special elections by about 11 points. They ended up winning the U.S. House popular vote by about 7 points, accounting for distorted vote totals in uncontested seats. That was an 8-point swing left since 2016.

Turnout in TN-07 was unusually high

But handicappers should be careful not to apply the full special-election swing when forecasting next year’s congressional midterms. Turnout in special elections tends to be much lower than in midterms, with lower-education voters and the party in control of the White House disproportionately staying home. This produces a sort of two-electorate dynamic to elections, where the voters turning out in specials are (currently) much more Democratic than those who vote in presidential races. Swings in specials tend to exaggerate subsequent swings in midterms.

Midterm turnout sits somewhere between turnout in special and presidential elections. In 2022, for example, voters across the country cast about 70% of the ballots as they did in the 2020 presidential elections. Special elections can have much lower turnout — like, 20 to 30% of totals in presidential elections.

However… turnout in Tuesday’s special election in Tennessee’s Seventh was not low. A rough guess is that about 180,000 votes will be cast in TN-07 for this special election. In the 2022 midterms, voters in the same seat cast 181,000 votes. So we are at around 99% of the typical midterm.

This means the 13-point swing in TN-07 (compared to 2024) is less likely to be distorted by low turnout. My best guess is that the 13-point swing on Tuesday translates to something like a 7- or 8-point swing for the midterms (turnout is still way below 2024, at 314k). My math is based on two factors: First, special election swings recently have been overestimating swings in midterms by about 2x, benefiting Democrats each time. But I’m hesitant to discount the full 50%, since turnout in TN-07 was so high. I’m assuming about 40% of the result in TN-07 was due to differential turnout patterns, and 60% was due to crossover voting — real changes in which party individuals vote for.

A swing of D+8 would put the national vote at D+6 in nominal terms — just shy of the Democrats’ D+7 “blue wave” in 2018. (Disclaimer: This estimate comes with uncertainty.)

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A way-too-early House seats model

Even D+6 would be huge for Democrats. We don’t know exactly what the 2026 U.S. House maps will look like in each state (the GOP ultra-gerrymanders in Texas and Indiana are pending Supreme Court decisions and further legislation), but according to data from The Downballot, Republicans won 23 House seats in 2024 that gave Donald Trump an 8-point or lower margin over Kamala Harris.¹ That would put Democrats at 238 U.S. House seats. (I personally think this is pretty optimistic for Democrats. But it’s what the data say right now.)

If you don’t want to use 2024 as the baseline, then we can use this spreadsheet of math produced by friend of the site Cory McCartan, Assistant Professor of Statistics & Political Science at Penn State. His modeling uses updated district lines and estimates that a D+6 House popular vote translates to around 235 seats:

Another wrinkle in the story is that the shift left has been very broad geographically. Rural areas have been affected just as much, if not more, than urban counties with lots of Democratic voters. If that happens in 2026, Republicans can say goodbye to a lot of their marginal red-leaning seats that include both city and rural voters. (Below graph courtesy of the NYT.)

A swing from R+2 to D+6 would also put the Senate in play. Giving Democrats 8 points would give them Ohio, Maine, and North Carolina, and put Iowa and Texas in play (especially if Republicans nominate Ken Paxton in the Lone Star Senate race).

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Wave watch

TN-07 didn’t flip, but in some ways that’s the point. When deep-red districts are behaving like swing seats, the safe assumption is that something big has shifted in the national environment. The burden of proof has shifted from people (such as yours truly) arguing a thermostatic backlash would sink Trumpism at the ballot box to those who argue that 2024 was some sort of pro-Trump realignment.

Looking ahead, the key question is whether these special election dynamics reflect a temporary mobilization of left-leaning voters as a byproduct of Trump’s presidency, or a more durable shift in voter preferences. If Democrats see the same shift in Congress next year as they saw in TN-07 Tuesday night, they’d win a landslide victory of 258 seats in the U.S. House. The more reasonable scenario — D+6 or so — still gives them a clear House majority.

Either way, the GOP will likely find itself defending an unusually wide array of seats next year, even in districts previously thought to be immune to national swings.

1. These are seats Democrats would be expected to win if you add 8 points of margin to their total. 8 because Republicans won the generic House vote by 2 in 2024, and 6 - -2 = 8).