The decision could complicate runner-up John Ratcliffe’s hopes of consolidating the anti-Hall vote in the May 27 runoff election.

Gigliotti’s endorsement comes after a tight primary race in which the 90-year-old Hall nabbed only 45 percent of the vote, falling short of the necessary 50 percent required to avoid a run-off. Ratcliffe won 29 percent.

( Also on POLITICO: Ralph Hall foe sees donor interest surge)

“If it’s not me then it’s gotta be Ralph. He’ll do a good job for another two years,” Gigliotti told POLITICO. “I can tell you this: it was a chore to get voters in this district to vote for anyone but Ralph.”

Gigliotti, who was endorsed by local tea party groups, brought in 16 percent of the vote on Tuesday.

GOP strategists in the district have said he carries a significant amount of name recognition and others have indicated his higher-than-expected turnout might have contributed to Hall’s low percentage.

“I could not be more pleased that Lou Gigliotti has offered his endorsement,” Hall said in a statement. “We received an overwhelming percentage of the vote yesterday and Lou’s endorsement helps solidify the fact that the electorate is more interested in someone with a proven conservative track record.”

Hall’s age and long tenure in Washington—his next term would be his 18th, and he’s the oldest House member in history —have been big issues in the primary. Gigliotti was particularly aggressive in his suggestion that Hall’s age should disqualify him from running.

Still, Gigliotti’s endorsement could hamper Ratcliffe just as he was gaining momentum. The 48-year-old runner-up, who self-funded much of his campaign, said Wednesday he’d seen a surge in donor interest.

Gigliotti stressed that he believes his supporters can easily get behind Hall.

“All of my voters were probably at one time Ralph Hall voters. I don’t think my vote can go to anybody else,” he said.