President Trump sharply criticized Rep. Thomas Massie (R-Ky.) during a visit to Kentucky on Wednesday, calling the seven-term congressman "the worst Republican congressman" in Congress' history and urging voters to replace him.

Trump made the comments during a visit to a packaging plant in Hebron, Kentucky, which is located within Massie's 4th Congressional District. The president accused Massie of opposing his agenda and encouraged Kentucky voters to oust him from Congress.

The criticism comes as Massie faces a May primary challenge, with Trump's opposition to the congressman becoming a significant factor in the race. Outside groups are now spending approximately $5 million in efforts to defeat Massie in the upcoming primary election.

Massie, who has served in Congress since 2012, has previously clashed with Trump and party leadership on various issues. The congressman has built a reputation as an independent voice within the Republican caucus, sometimes breaking with party positions.

The substantial financial investment by outside groups reflects the heightened attention on the race, particularly given Trump's direct involvement in opposing an incumbent Republican congressman. The May primary will test whether Trump's influence can successfully challenge a sitting Republican member of Congress in his own district.