The anxiety among some Republicans foreshadows what is shaping up to be a partisan brawl that could put a hefty target on their backs, either with constituents or with Trump himself -- neither of whom GOP lawmakers are eager to cross. If they don't sufficiently defend Trump, they are bound to invite outrage from the base. Yet if they deny the former President's role in the attack on the Capitol, they will be cast as whitewashing history.

So most Republicans would rather keep their heads down as the probe plays out in the House, especially those representing more moderate-leaning districts.

What also remains uncertain is whether McCarthy will choose Republican hardliners, including many who voted to overturn the electoral results on January 6 or have publicly downplayed the events of that day. Some of those Republicans have signaled a willingness to serve on the committee, while McCarthy has dodged questions about whether they could win one of the five GOP spots.