A member of the House Freedom Caucus endorsed a primary challenger to the group’s chair, a move that is sure to inflame tensions in the hard-line conservative group.

Rep. Warren Davidson (R-Ohio) on Sunday endorsed John McGuire, a Virginia state senator and former Navy SEAL, in his challenge to Rep. Bob Good (R-Va.), the Freedom Caucus chair.

“In Virginia's 5th District, John McGuire is conservative and effective. He will work well with others to deliver conservative results,” Davidson said in an endorsement statement shared by McGuire’s campaign on the social platform X. “I look forward to serving with him in the 119th Congress to support President Trump and the America First agenda. Drain the swamp!"

The race for the central Virginia district, which will be decided Tuesday, is one of the most continuous primary campaigns of the year and could result in the first incumbent loss of the cycle.

Former President Trump endorsed McGuire, an apparent effort to punish for Good endorsing Florida Gov. Ron DeSantis (R) for president last year, despite Good’s quick public support for Trump after DeSantis dropped out. And Good’s vote to remove former Speaker Kevin McCarthy (R-Calif.) prompted many of his House colleagues, as well as McCarthy himself, to support and campaign for McGuire.

Good has gotten support, though, from other Freedom Caucus members and many of Trump’s allies — including Rep. Matt Gaetz (R-Fla.) and Rep. Byron Donalds (R-Fla.), a reported contender to be Trump’s running mate. Over the weekend, Freedom Caucus members Chip Roy (R-Texas), Andy Biggs (R-Ariz.), and Andrew Clyde (R-Ga.) campaigned for Good ahead of primary election day.

But Davidson’s endorsement, which was first reported by Politico, put tensions within the hardline conservative group on display.

In December, Davidson said he would not seek reelection to the Freedom Caucus Board after it recommended Good to be the group’s next chairman, writing in a letter to colleagues that the group “often relies too much on power (available primarily due to the narrow majority) and too little on influence with and among our colleagues,” and that it is “not a strong foundation for success.” Those concerns culminated with Good’s recommendation to be chair, Davidson wrote.

Rep. Marjorie Taylor Greene (R-Ga.), who was removed from the Freedom Caucus amid personal clashes with its members and publicly disagreeing with them, has also endorsed Good’s challenger McGuire.