President Donald Trump on Monday urged supporters to vote out Rep. Thomas Massie, R-Ky., in his upcoming Tuesday primary, marking his latest effort to neutralize the libertarian-leaning lawmaker.

"The worst Congressman in the long and storied history of the Republican Party, is Thomas Massie. He is an obstructionist and a fool. Vote him out of office tomorrow, Tuesday. It will be a great day for America!" he posted on Truth Social.

Trump previously backed a primary challenge to Massie, before endorsing him in 2022. The Kentucky Republican's libertarian streak has frequently seen him clash with his own party on budgetary and foreign policy matters.

Massie faces the Trump-endorsed Ed Gallrein on Tuesday, in what has become the most expensive Republican House primary in history. Driving much of the expenditure has been pro-Israel groups frustrated with Massie's skeptical attitude toward U.S. support for that country.

Ben Whedon is the Chief Political Correspondent for Just the News. Follow him on X.