A change in the overall political mood could move some of these races into tossup territory. Here are a few to keep an eye on:

The decision of Representative Abigail Spanberger, a Democrat, to run for governor turns her Democratic-leaning seat into a free-for-all. Seven Democrats have declared for the primary on June 18, including Eugene Vindman, the twin brother of Alexander Vindman, the military officer on the National Security Council who blew the whistle on Mr. Trump’s efforts to press Ukraine’s leader into announcing an investigation of Mr. Biden. Eight Republicans are running.

  • Biden +6.8

  • Democrat +5 in 2022

Nevada’s three Democratic House members proved their resilience in 2022 when all were re-elected in a year when Republicans recaptured the state’s governorship. In 2024, the state is a presidential and Senate battleground. Representative Susie Lee may have the toughest district to defend against the winner of the Republican primary on June 11.

  • Biden +6.6

  • Democrat +4 in 2022

Representative Scott Perry, a Republican leader of the House Freedom Caucus, has never moderated his conservative politics to match his swing district, even after the committee that investigated the Jan. 6, 2021, attack on the Capitol excoriated him for his role in trying to overturn the election. This year, a well-known personality, the Pennsylvania newscaster Janelle Stelson, has chosen to run as a Democrat and raise Jan. 6 as her main cause. First, she needs to get through the primary on April 23.

  • Trump +4.1

  • Republican +8 in 2022

In 2022, Adam Frisch, a Democrat, startled many people, including his opponent, Representative Lauren Boebert, when he came within 546 votes of defeating her. He was seeking a rematch in this vast district that stretches from the western slopes of the Rockies through most of southern Colorado, but Ms. Boebert, a conservative firebrand with a flare for grabbing attention, bowed out and moved to run in a district in the eastern part of the state. Prevailing this time against the winner of the 10-candidate Republican primary on June 25 will be even harder for Mr. Frisch. But from his days as Ms. Boebert’s nemesis, he has raised a staggering $10.8 million.

  • Trump +8.3

  • Republican +0.2 in 2022

George Santos put this Long Island district on the map with his fraudulent résumé, congressional histrionics and remarkable ouster from the House. A solid victory by Tom Suozzi, a Democrat, in a special election to replace Mr. Santos has convinced many handicappers that the seat will remain in his hands this November. But Republicans won it in 2022 with Mr. Santos, and eight of them have lined up ahead of the primary on June 25 to try to take it back.

  • Biden +11.3

  • Republican +8 in 2022

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