Originally, progressives weren’t going to let the roads-and-bridges bill pass without their preferred legislation getting an affirmative vote first. But with the exception of the Squad, the progressives mostly did vote to let infrastructure proceed in exchange for promises on reconciliation. Why? Because they trust Biden. He made promises, and they believe he intends to keep them, even as progrssives fret that the moderates will simply move the goalposts once the Congressional Budget Office releases its reconciliation bill score.

If Biden cannot deliver, however, it will be disastrous for Democratic unity. Not only are they running out of chances to pass their legislative agenda — presumably, few lawmakers will want to take tough votes in an election year, and their majorities could easily be gone in 2023 — but the distrust between the party’s factions would spin out of control. Senate Minority Leader Mitch McConnell (R-Ky.) could go on extended vacation without having to worry about Democrats achieving anything on Capitol Hill.

Progressives would also likely wind up being led by the most aggressive members of their ranks in the event of a Biden failure, because they’ll feel that those who sided with leadership made a serious strategic error.