Does Chait’s formulation also apply to Democrats like Sinema and Sen. Joe Manchin (D-W.Va.), moderates who are among the main obstacles both to party unity and to passing Biden’s agenda? It’s discomfiting to think so. After all, both senators are arguably doing the democratic thing by staking out stances somewhat to the right of their party — Manchin represents a deep red state, after all, while Sinema’s Arizona constituency is fairly purple. As always, it’s important to remember that in a 50-50 Senate, Democrats won’t get anything done without their votes. Treating them like the enemy isn’t likely to accomplish anything.

Then again, the Democratic agenda isn’t getting very far very fast with them on board. And it’s not at all clear that Manchin or Sinema have any misgivings that they might be increasing the chance that Biden’s presidency fails, thus improving the odds that Trump returns to power. If nothing else, it would be nice if they signaled that they understand the stakes.

It’s easy to be unified when you’re in the opposition: There is no agenda that can be enacted, so every vote and every piece of messaging can be focused entirely against the people and party in power. Once your party does attain power, decisions must be made, priorities set, and votes taken — and that process can get complicated. That’s where Democrats find themselves. Ultimately, the party will be judged on what it gets done, and whether it can halt the decline of America’s democracy. But right now, Democrats are busier fighting each other.