My half-baked cloak-and-dagger theory is that Biden tanked the negotiations deliberately, to put more pressure on Manchin at a moment when he’s already under tremendous pressure from the left to figure out a way to pass their agenda along partisan lines. The sooner he shows Manchin that the GOP won’t agree to anything, the sooner Manchin has to decide once and for all if he’s movable on doing things by a simple majority or if this is how it’s going to go for the rest of Biden’s presidency.
Honestly I don't know where people think this magical "pressure" is going to come from. The dude has made his opinion on both the filibuster and reconciliation crystal-clear in speech and writing. Repeatedly.
Chuck Schumer can't bring any pressure on Manchin. The moment he does, Manchin could flip Republican and Chuckie is back to bring minority leader. Nobody in West Virginia is putting pressure on Manchin to cave to the Democrats.
The media and Democrats (I repeat myself) can't move Manchin. He doesn't give a s--t.