Some of them do admit that — when they’re cornered. I’m thinking of Dan Crenshaw being confronted by an election truther at a fundraiser in August and telling the guy that he was kidding himself if he believed there was such widespread fraud that it flipped the result in multiple states. There’s a cohort of hardcore populists within the House GOP whose loyalty to Trump is such that they’ll eagerly parrot any conspiracy theory he likes but most GOP reps who are asked about this tend to mumble something noncommittal about “election integrity” and “unanswered questions” before changing the subject.