Dogged by his vote to impeach President Donald Trump in 2021, Sen. Bill Cassidy (R-LA) lost his bid for reelection on Saturday night, finishing in third place in the Louisiana Republican primary behind Trump-endorsed Rep. Julia Letlow (R-LA) and state Treasurer John Fleming.

Letlow and Fleming, the top two finishers, will now compete in a runoff, which will be held on June 27. Cassidy only received 25% of the primary vote, lagging well behind Letlow, who received 45% of the vote, and Fleming, who won 28%.

The race offered another strong signal that Trump’s backing is the most important factor in Republican nomination fights. Of the seven Republican senators who voted to convict Trump at his 2021 impeachment trial, only two remain in the Senate. One of them, Sen. Susan Collins (R-ME), faces her own difficult reelection. 

The results also come two weeks after Trump and his political allies successfully ousted five Republican state senators in Indiana primaries, after they opposed the Trump administration’s push to redraw the state’s congressional lines to further favor Republicans.

Cassidy, first elected to the Senate in 2014, had long been one of the more bipartisan members of his caucus, using his experience as a doctor to take the lead on health care issues. He drew close scrutiny for his decision supporting Robert F. Kennedy, Jr. to be confirmed as health and human services secretary in his role as HELP Committee chairman, despite holding serious misgivings over Kennedy’s record opposing vaccine requirements. 

In his concession speech, Cassidy told supporters: “When you participate in democracy, sometimes it doesn’t turn out the way you want it to. But you don’t pout. You don’t whine. You don’t claim that an election was stolen from you.” 

The next big test of Trump’s influence in party politics will come on Tuesday, when Rep. Thomas Massie (R-KY), a virulent opponent of Israel, will face off against Trump-endorsed challenger Ed Gallrein, a Navy veteran. Trump allies and outside pro-Israel groups have poured millions into the race to defeat Massie. Polls show the race is competitive, with Gallrein holding late momentum.