Photo: Saul Loeb/AFP via Getty Images

It is always darkest, John McCain used to say, before it gets totally black. So it is for the American center-left right now. Bernie Sanders is currently favored to win the nomination, a prospect that would make Donald Trump a heavy favorite to win reelection, and open the possibility of a Corbyn-esque wipeout. While Sanders has not expanded beyond a minority of the party, he has consolidated support of the party’s left wing, and while its mainstream liberal wing is split between numerous contenders, it is hard to see how the situation is likely to improve soon. Indeed, it could get worse, much worse.

The liberal conundrum begins with Joe Biden. The former vice-president led national polls until very recently, and has been the most plausible mainstream liberal candidate. At the same time, doubts about his ability to handle the rigors of the campaign at an advanced age have caused the Democratic Party to withhold the institutional support it gave Hillary Clinton. Yet his name was big enough to preclude a younger, more vigorous Democrat from emerging in the ideological space he occupied. Beto O’Rourke, Cory Booker, and Kamala Harris all tried and failed to run as ideological heirs of Barack Obama, because Obama’s actual partner was still there.

Yet Biden underperformed in Iowa, and his campaign appears to be deflating, at least momentarily. So what to do?

One strategy would be to rally around him, on the grounds that no other candidate has or will have his name recognition and ties to black voters. The other strategy is to hope his campaign collapses as quickly as possible, so that another contender can emerge. (More about them below.) At the moment it is not clear which strategy makes sense. And in the absence of an effective party to coordinate, the most likely scenario is a combination of the two: Some Democrats back Biden, others defect, and others wait to see what happens. That would be the worst possible outcome: a long, slow, painful death that prevents another liberal from taking his place and allows Sanders to gain unstoppable momentum.

In the meantime, it seems hard to imagine how Biden or a Biden alternative could emerge in the next three contests. The next contest is in New Hampshire, which borders the home states of both Sanders and his closest ideological counterpart, Elizabeth Warren. After that comes Nevada — which, like Iowa, uses the caucus system, which has a fraction of the voting participation of primaries and reward the kind of intense organization Sanders has mastered.

Then comes South Carolina. Biden has been pointing to this state, where he has always led, as his firewall. But will it hold if he is coming off three straight defeats? It is possible that by this point, Biden will have been supplanted in the center-left lane by Pete Buttigieg or even Amy Klobuchar. However, neither has the inroads to the state’s black community that Biden built, which means neither would be able to count on its support as a bulwark against the left-leaning electorates in the previous states. Also, as an additional morbid touch, the South Carolina primary will feature an organized influx of Republicans voting for Sanders in a specific plan to boost what they see as Democrats’ weakest nominee.

So it is entirely possible that, following South Carolina, Sanders will have won three or all four of the contests. If nobody has emerged as a viable alternative by then, Michael Bloomberg’s campaign will be stepping in. It is extremely hard to estimate the probability of success of a candidate who has skipped the first four races. FiveThirtyEight’s model currently gives Bloomberg less than a one percent chance of winning.

To be sure, if Bloomberg is the last Democrat standing against Sanders, he may well attract substantial support from Democratic elected officials and put up a strong fight. Still, he would face enormous opposition from the left. This is, after all, a billionaire who endorsed George W. Bush in 2004. And while the left has previously whipped itself into an angry frenzy against, successively, O’Rourke, Biden, Harris, and Buttigieg, the rage against Bloomberg would reach a new level.

At that point, the victory scenario would involve a long, bloody struggle all the way to the convention, with the Sanders movement claiming at every step of the way that the party is rigging the race against them, culminating in a convention where his enraged supporters will again try to shout down the proceedings. Unless one of the non-Bloombergs can somehow get off the mat and defeat Sanders, this is probably the best-case scenario for liberals at this point. It seems more probable that Sanders crushes the field and brings his historically unique suite of liabilities to the ticket.

At the moment, the party is melting down over a vote-reporting fiasco in Iowa. In time, we liberals may look back at this moment as a high point.