U.S. Rep Mike Bost has won the Republican nomination in southern Illinois after a hard-fought primary battle with former state Sen. Darren Bailey.

Bailey, the 2022 GOP nominee for Illinois governor, challenged the five-term incumbent, claiming he was not conservative enough for the district that encompasses virtually the entire bottom one-third of the state. He sought the endorsement of former President Donald Trump, but Trump chose Bost.

ILLINOIS REPUBLICAN CONGRESSIONAL CANDIDATES FIGHT FOR FAVOR OF TRUMP SUPPORTERS

Bost thanked Trump during a speech to supporters late Tuesday where he claimed victory. He emphasized the need for party unity.

"I don't compromise my morals, but this nation is built on finding common ground," he said.

Bailey, 57, attempted to capitalize on the shift to the right in the 12th District after the 2020 Census. A Marine Corps veteran, the 63-year-old Bost is chairman of the House Committee on Veterans’ Affairs and has seats on the Agriculture and Transportation and Infrastructure committees. He made the case that seniority, know-how and relationships he’s developed allow him to provide better constituent service and move legislation helpful to the district more readily than a newcomer who needs "on-the-job training."

Bost is widely expected to win in November when he will face Democrat Brian Roberts, a Carbondale attorney.