1. Lawmakers fled the House in droves, ensuring a reshaped Congress in 2027

Viewed as the chamber of Congress most likely to change hands in the midterms, the House saw significant turnover this cycle, with 74 members departing, the most since 1992, according to a tally from the Pew Research Center. Some outgoing lawmakers retired, while others ran for other offices, but generally didn’t fare particularly well – only 13 made it through primaries for governorships, the Senate or other offices, with the remaining 15 were rejected by voters.

Among representatives who sought re-election to the House, 11 lost their primaries, the second-highest total since 2022. Seven of these were Democrats, two of whom – Julie Johnson and Al Green – were unseated by other Democratic incumbents after they were redistricted by Texas Republicans to compete against each other.

2. Leftists, especially Democratic socialists, rocked the party …

Of the five House Democrats who lost their primaries to newcomers, four were booted by leftist candidates with ties to the Democratic Socialists of America (DSA). In New York, Congressional Hispanic Caucus chair Adriano Espaillat fell to DSA member Darializa Avila Chevalier and congressman Dan Goldman was ousted by former DSA member Brad Lander, while DSA member Claire Valdez also won the primary to replace retiring congresswoman Nydia Velazquez.

In Colorado, DSA member Melat Kiros unseated 30-year incumbent Diana DeGette, and in Michigan, the DSA-endorsed Donovan McKinney beat congressman Shri Thanedar. All are expected to win their seats in the midterms, as their districts are heavily Democratic.

“A lot of people were hoping that it was a blip, like oh well, this is a special case,” said the DSA-endorsed Chris Rabb, who is expected to be elected to the House after winning the Democratic primary in deep-blue Philadelphia. “We showed them a different way. So I think all of those things make this election cycle uniquely powerful in ways that most people could not anticipate, myself included.”

The fifth sitting Democrat to lose renomination was John Larson. His challenger, Luke Bronin, 47, successfully argued to voters that it was time to replace the 78-year-old incumbent with a younger candidate.

3. … but centrists are on the frontlines

The battle for the House will not be decided in safe blue seats, but rather the 21 districts that the Cook Political Report considers to be toss-ups. In those districts, the nominees are almost entirely backed by the Pacs of either the center-left New Democrat Coalition, or the moderate Blue Dogs, which centrists say bolsters their arguments that their policies most closely align with the voters who determine control of Congress. “If Democrats are to win the majority in the House and/or the Senate, it will be because moderates flip seats from red to blue,” said Matt Bennett, an executive vice-president at the thinktank Third Way.

There are exceptions to the trend: former DSA member William Lawrence won the Democratic nomination to take on Republican incumbent Tom Barrett in a swing Michigan congressional district, while in that state’s Democratic Senate primary, Abdul El-Sayed beat congresswoman Haley Stevens, who was backed by much of the party establishment.

4. Anti-incumbent sentiment among Democrats had its limits

The DSA’s wins reintensified debate among Democrats over the political direction of the party, but the left-wing movement’s momentum was not absolute. In Missouri, DSA member Cori Bush failed in her primary challenge against congressman Wesley Bell, who had unseated her two years ago. Hawaii congressman Ed Case fended off state senator Jarrett Keohokalole, who had challenged him from the left and argued it was time for generational change. In Massachusetts, congressman Seth Moulton made a similar argument about the Democratic senator Ed Markey, though in this case Moulton was the moderate candidate and Markey the progressive.

It didn’t work, and Markey won renomination, as did other congressional Democrats in the state who faced primary challenges. In Colorado, state senator Julie Gonzales mounted an unsuccessful left-wing challenge to Democratic US senator John Hickenlooper, while in Washington, moderate congresswoman Marie Gluesenkamp Perez again won the Democratic nomination in her right-leaning district against several challengers.

5. Trump flexed his muscles, with much success

As always, Trump sought to play kingmaker in the primaries, endorsing candidates who hewed to his agenda and seeking revenge against those who had broken with him, however small their transgressions. Kentucky congressman Thomas Massie lost his primary after the president campaigned against him, and the president’s decision not to make an endorsement in Texas representative Dan Crenshaw’s primary was likely a factor in him losing the Republican nomination. Trump successfully ousted Louisiana senator Bill Cassidy – who voted to convict him after January 6 – as well as Texas senator John Cornyn, for comparatively murkier reasons.

The president may rue the latter decision – recent polls have shown the Democratic nominee James Talarico with a slight lead over Trump’s preferred candidate, Ken Paxton. All told, it was a successful primary for Trump – an analysis of his record by USA Today shows nearly 97% of the candidates he backed in congressional and gubernatorial races won their primaries. There were a handful of misses – five gubernatorial candidates won their primaries without Trump’s endorsement, along with four House aspirants.

6. Aipac spent, for better or worse

The American Israel Public Affairs Committee (Aipac) waded into some primaries at a particularly fraught moment for supporters of the Middle Eastern ally. Surveys show that some Republicans and many Democrats now hold negative views of Israel, amid accusations it carried out a genocide in Gaza, and many of the left-wing candidates who ousted Democratic House incumbents did so after attacking their ties to Aipac. Through its United Democracy Project Super Pac, the group nonetheless scored some wins, including Ed Gallrein’s defeat of Massie in Kentucky, Adrian Boafo’s victory in the Maryland primary to replace veteran House Democrat Steny Hoyer, and Bell’s defense against Bush’s primary challenge in Missouri.

But the group failed to keep El-Sayed from defeating Rogers in the Michigan Senate primary, despite spending more than $30m in that race, or prevent progressive Aisha Wahab from winning a special election to replace former congressman Eric Swalwell in California.

7. Some candidates fell to scandals, others pressed on

Several candidates who ran for office were derailed by scandals. Graham Platner won the Democratic primary to take on veteran Republican senator Susan Collins in Maine, but dropped out amid accusations of sexual assault and misconduct. Swalwell ran for governor of California but exited that race and resigned his US House seat after he, too, was accused of sexual assault. North Carolina Republican congressman Chuck Edwards won his primary but ended his re-election campaign after the House ethics committee said he likely broke rules against sexual harassment, but Republican congressman Max Miller remains in the race amid accusations of domestic violence against his ex-wife.

In other instances, the GOP used the primaries to dispose of problematic lawmakers in their ranks. Andy Ogles, a congressman with a history of homophobic and Islamophobic statements, lost in Tennessee after the Republican governor endorsed his challenger and a Super Pac backed by the renewable energy industry spent against him, and scandal-plagued congressman Cory Mills was defeated after other Florida Republicans endorsed his challenger.