Fresh off his takedowns of GOP dissenters in this month's primaries, President Trump is already making a list of Republicans who could be on his 2028 chopping block.Why it matters: Trump's string of primary wins over GOP adversaries has reaffirmed his dominance over the party — and now he's looking to extend that influence after he leaves office in January 2029.What they're saying: "Do not ever doubt President Trump and his political power. F**k around, find out," White House communications director Steven Cheung wrote on X Tuesday after Trump-backed Ed Gallrein unseated Rep. Thomas Massie (R-Ky.), a frequent critic of the president.Zoom in: Massie's loss followed a weekend in which another of Trump's longtime targets — Sen. Bill Cassidy (R-La.), who drew Trump's wrath five years ago by voting to convict him for his role in the Jan. 6 riot — failed to make a runoff for the Senate seat.This week, Trump hasn't been shy about identifying possible future targets in his party:1. Colorado Rep. Lauren Boebert. Trump took to Truth Social over the weekend to solicit a primary challenger to Boebert, whom he called "weak-minded" and "very difficult."The president was infuriated that Boebert had campaigned for Massie. "I knew the risks when I agreed to stand by my friend Thomas Massie," Boebert said in response.Boebert also ran afoul of the president's team by calling for the release of the Epstein files and for backing then-Virginia Rep. Bob Good against a Trump-endorsed primary challenger in 2024.2. Kentucky Sen. Rand Paul. Trump repeatedly attacked Paul for supporting Massie, who shares the senator's libertarian instincts.The president also has criticized Paul for voting against Trump's "big, beautiful bill" and opposing his decision to attack Iran.3. Ohio Rep. Warren Davidson. Davidson is another GOP House member whom the White House has signaled could be targeted. White House Press Secretary Karoline Leavitt said last year the president believed Davidson should face a primary challenge for initially opposing the bill. Davidson, however, ended up without a serious Republican challenger this year.But Davidson continues to frustrate the White House, most recently by backing Massie's reelection.4. Pennsylvania Rep. Brian Fitzpatrick. Trump on Wednesday tore into Fitzpatrick — who represents a swing suburban Philadelphia district that Democrat Kamala Harris won in 2024 — for "vot[ing] against me all the time.""You know what happens with that? It doesn't work out well," Trump added.Fitzpatrick and Massie were the only two House Republicans to vote against Trump's tax and spending megabill. More recently, Fitzpatrick has opposed Trump's request for up to $220 million to help fund the president's controversial White House ballroom. White House Deputy Chief of Staff James Blair played down the idea that Trump would try to unseat Fitzpatrick, who as a vulnerable incumbent faces pressure to show independence from his party.Trump "has a long history with Congressman Fitzpatrick and I think the president understands very clearly that there are some things he disagrees on," Blair told CNN's Jake Tapper."I think [Fitzpatrick will] be successful in the fall ... The president does allow for disagreement within the party but there are some things that, you know, he's not gonna allow for disagreement on."Between the lines: Trump is increasingly confident he can boot anyone who crosses him, and he has the backing of a sophisticated and well-funded political operation that he lacked during his first term.Trump's anti-Massie super PAC was led by Chris LaCivita and Tony Fabrizio, who were senior advisers on his 2024 campaign."Trump's political operation was critical to the win. Their ads were absolutely devastating and immensely impactful," said Kentucky-based GOP strategist Jake Cox.Yes, but: Trump's eagerness to target Republicans up for election in 2028 isn't without risk. The president has narrow congressional majorities that could disappear this year, and can't afford to alienate too many GOP lawmakers.Cassidy, for example, has made clear that in his last months in office he plans to oppose several pieces of Trump's legislative agenda. What's next: Trump must decide whether he wants to oppose Rep. Nancy Mace (R-S.C.) — who co-led a push with Massie and Boebert to force the release of the Epstein files — in the June 9 primary for South Carolina governor.