McCarthy's committed the sin of making some type of deal with the White House, rather than being willing to have the global economy crash. It's not sitting well with the expected wing of his party.
This has revealed that the rump GOP has not quite been entirely engulfed by the Trumpist cult; that some at least retain a vestigial interest in the public good. Or at least, their own good.
It's a foregone conclusion that McCarthy can't pass any debt ceiling bill without Dem help. Also, that accepting Dem help will lead the Trumpists to trigger a vote on McCarthy's Speakership, which he'd only survive with yet more Dem votes.
These splits are hardly new - they date to Gingrich, and before. They're certainly the evolution of the Tea Party, which made a "House GOP Majority" fictitious under Boehner and Ryan, who you'll recall blamed Dems for not assisting them in passing odious legislation. Just insufficiently odious to unite the Right.
Comment