WASHINGTON, May 16 (Reuters) - U.S. President Donald Trump threatened a primary challenge on Saturday against ‌hardline conservative U.S. Representative Lauren Boebert, until ‌now a staunch Trump ally, after she campaigned for maverick ​Representative Thomas Massie in his Kentucky district.

• "Boebert is campaigning for the Worst 'Republican' Congressman in the History of our Country, Thomas Massie, of the Great Commonwealth of Kentucky, ‌and anybody who ⁠can be that dumb deserves a good Primary fight!" Trump wrote on Truth ⁠Social.

• Trump has vowed to unseat Massie, a Republican who has defied the president in Congress over ​major legislation ​and the Iran war ​and led his party's ‌drive to release government files on the late financier and convicted sex offender Jeffrey Epstein.

• The president's quest to unseat Massie poses a test for his hold on the Republican Party.

• Trump's social ‌media post came hours after ​Boebert made campaign appearances for ​Massie, who faces ​Trump-endorsed challenger Ed Gallrein, a retired ‌Navy SEAL, in Tuesday's Republican ​primary in ​Kentucky.

• "Is anyone interested in running against Weak Minded Lauren Boebert in Colorado’s Fourth Congressional District?" Trump ​posted. "Just let ‌me know, or announce your Candidacy, and I ​will be there for you!"

(Reporting by David ​MorganEditing by Rod Nickel)