Sen. Bill Cassidy (R-La.) just lost his seat — a key victory for President Donald Trump’s revenge tour this cycle.

Rep. Julia Letlow, the Trump-backed candidate, and state Treasurer John Fleming advanced to a runoff in the Louisiana GOP Senate primary on Saturday, with Cassidy finishing in third place.

It’s a remarkable result: Cassidy is the first senator of either party to lose in a primary since 2012. The two-term senator and chair of the powerful Senate Health, Education, Labor, and Pensions (HELP) Committee failed to even make the runoff, finishing with roughly a quarter of the vote.

Both Letlow and Fleming benefited from MAGA voters’ frustrations with Cassidy for his 2021 vote to convict Trump on impeachment charges related to the Jan. 6 insurrection, and for his skepticism of Trump’s decision to nominate Robert F. Kennedy Jr. as Health and Human Services secretary.

The president, who has been itching to oust Cassidy, finally got his wish Saturday. The result follows Trump’s successful attempts to oust several GOP state senators in Indiana last month over redistricting clashes.

Letlow, a three-term representative from north Louisiana, jumped into the race with Trump’s endorsement, a huge boost in the deep-red state. Gov. Jeff Landry also endorsed her and worked behind the scenes to help her campaign, and the Make America Healthy Again PAC committed $1 million to supporting her.

Fleming, a former member of Congress and White House aide under Trump, drew deep grassroots support during his campaign and was able to cut into Letlow’s polling lead in the final days of the race.

The runoff will extend an already expensive battle for the GOP nomination to late June. Early polls suggest a tight race between Letlow and Fleming, though Letlow had a clear advantage in the first round of voting.