…Because Republicans have a slim 222–213 majority in the House, any group of five lawmakers can hold considerable leverage by threatening to vote against a bill. That’s the same dynamic that allowed a small breakaway faction of Republicans to hold up McCarthy’s election as speaker in January—but now there are stakes that actually matter, as the Treasury is tipping dangerously close to a possible default if the debt limit is not raised in the coming weeks.

McCarthy’s proposal marries a debt limit increase to a series of other policy changes, most importantly a rollback of the omnibus spending bill passed in December by the outgoing Democratic majority…