In Kentucky, in Tuesday’s marquee House race, the big winner among Republicans was President Trump.

In Pennsylvania, in a test of the strength of the Democrats’ far-left flank, the big winner was Representative Alexandria Ocasio-Cortez.

And in other House primaries, the results offered new information about the battle for the majority.

Here’s a closer look at what happened in the most notable contests:

Another notch in Mr. Trump’s belt.

Republican primary voters in Kentucky’s Fourth Congressional District voted decisively against Representative Thomas Massie, so starting next year, Ed Gallrein, his Trump-backed challenger, almost certainly will be their member of Congress instead.

Mr. Massie, 55, who was first elected in 2012, is the M.I.T.-educated engineer Mr. Trump took to calling a “moron” and a “fool” because he voted against the president’s “big, beautiful bill,” successfully pushed for the release of the Epstein files and has opposed the conflict in Iran. Mr. Gallrein, 68, who lost his election for a seat in the State Senate in 2024, is a farmer, a former Navy SEAL and the “warm body” Mr. Trump enlisted and endorsed to dislodge one of his most devoted critics in the G.O.P.

“For my colleagues, this election is about, can we deviate occasionally from the plan,” Mr. Massie told The New York Times a few weeks back, “and still survive our primaries?”

In his case, this year, the answer was no.

Mr. Massie’s loss marks Mr. Trump’s latest victory in his ongoing retribution-seeking efforts and reinforces his dominance in the G.O.P. despite his consistently sinking approval ratings among Americans more broadly.

Get ready to know the name Bob Brooks.

In Pennsylvania’s Seventh District, a consummate swing area in a consummate swing state, the winner of a hotly contested four-person Democratic primary was a working-class avatar with unusually broad party appeal.

Bob Brooks, a retired firefighter, union leader and snowplow driver sporting endorsements from top Democrats ranging from Gov. Josh Shapiro of Pennsylvania and former Transportation Secretary Pete Buttigieg to Senators Bernie Sanders and Elizabeth Warren, beat Lamont McClure, a former county executive; Carol Obando-Derstine, a former senior adviser to former Senator Bob Casey; and Ryan Crosswell, a Marine and former federal prosecutor. And it wasn’t close. Up next in November in a district Trump barely won: Representative Ryan Mackenzie, a first-term Republican incumbent, who also barely won.

“Democratic primary voters, their elected officials and leaders across the party demand a Democratic Party focused around working people,” said Tommy McDonald, a Brooks consultant. “Someone with Bob’s profile is going to drive a truck over Ryan Mackenzie at the ballot box,” Mr. McDonald added. “A fire truck.”

A win for Ms. Ocasio-Cortez — in Philadelphia.

In Pennsylvania’s Third District, one of the country’s bluest, the winner of an internecine brawl to succeed retiring Representative Dwight Evans was Chris Rabb, an anti-ICE, anti-establishment state representative and self-described “radical” democratic socialist endorsed by Ms. Ocasio-Cortez.

Rabb, 56, beat Sharif Street, a state senator and a former chair of the Pennsylvania Democratic Party, and Dr. Ala Stanford, a pediatric surgeon and the founder of Philadelphia’s Black Doctors COVID-19 Consortium.

“Democratic voters want bold leaders right now,” said Nick Gavio, a spokesman for the Working Families Party, which endorsed Mr. Rabb. “Leaders willing to push the envelope — and Rabb does that.”

“It feels like a real movement,” a woodworker who supported Mr. Rabb told a reporter from the Philadelphia Inquirer at the candidate’s election night party.

The other Kentucky district receiving some attention.

Zach Dembo, a former Navy J.A.G. officer, federal prosecutor and aide to Gov. Andy Beshear, bested former state representative Cherlynn Stevenson in the Democratic primary in Kentucky’s Sixth District — setting up a matchup in November with Ralph Alvarado, the Trump-backed Republican nominee aiming to succeed Andy Barr, the Trump-backed G.O.P. gubernatorial nominee.

Republicans are favored in the district, but national Democrats are emphasizing Mr. Dembo’s political profile. And without an incumbent running, there may be an opening for Democrats to make the race more competitive.

“Zach Dembo is exactly the type of candidate that is going to help Democrats take back the House majority,” said Suzan DelBene, the chair of the Democratic Congressional Campaign Committee.