When the histories are written, it won’t be Labour leader Jeremy Corbyn’s fault that UK voters chose Leave. That “honour” will go to David Cameron by a Shropshire mile. But the leftist Corbyn behaved by all accounts disgracefully, never willing to put any of his position or prestige really on the line to avert the catastrophic outcome.

And it makes me wonder about something similar that’s going to happen here in the United States in a few months’ time, when our version of Jeremy Corbyn (you know who I mean) will be called upon to speak forcefully against our version of Brexit (again, you know what—or who—I mean).

But first, Corbyn. Back during his campaign for Labour leader, the Brexit issue came up, since that was right after Cameron first bruited the referendum idea, and Corbyn always expressed a certain ambivalence toward the EU. So fair enough. But when the eleventh hour came, and it was obvious that Leave would be disastrous and that the biggest winners from Brexit were going to be comb-less demagogue Boris Johnson, white ethno-nationalist Nigel Farage, and after them the international rogues’ gallery that includes names like Wilders, Le Pen, Putin, and Trump, he still did nothing. Not long before the vote, he said he’d been “no great fan” of the European Union.

I knew all this, and I recognized it as the usual juvenile leftist dialectics: If it’s bad for the City, it must be good. You know the kind of thing. But then Saturday evening I read this, and my contempt soared:

Remain campaign operatives floated a plan to convince Corbyn to make a public gesture of cross-party unity by appearing in public with the prime minister. Polling showed this would be the “number one” play to reach Labour voters.

Senior staff from the campaign “begged” Corbyn to do a rally with the prime minister, according to a senior source who was close to the Remain campaign. Corbyn wanted nothing to do with the Tory leader, no matter what was at stake. Gordon Brown, the Labour prime minister whom Cameron vanquished in 2010, was sent to plead with Corbyn to change his mind. Corbyn wouldn’t. Senior figures in the Remain camp, who included Cameron’s trusted communications chief Craig Oliver and Jim Messina, President Obama’s campaign guru, were furious.

The “number one” play to reach Labour voters. And he wouldn’t do it. If ever there was a matter on which to put party differences aside for a mere few days and make a couple of appearances together, it was surely this one. A mere few days. Then, right after Remain had won, go back to attacking Cameron about all the usual things, in plenty of time for next Wednesday’s question time.

But Corbyn wouldn’t do it. If nothing else, self-preservation should have guided him, because if Scotland, which backed Remain in huge numbers, leaves the UK as it is threatening to, Labour is all but dead. Labour without Scotland is like the Democrats without California. Or something more or less like that. It’s not remotely the outcome I’d prefer, but it is very much the outcome that this horse’s arse deserves. But it’s always the same with people like this. To true ideologues, practical politics is bourgeois; beneath them. Predictably and rightly, Corbyn now faces a coup.

All this brings us to Bernie Sanders.

Last Friday, Sanders was asked about the Brexit vote on Morning Joe. He essentially endorsed the result, or at least blithely rationalized it:

What this vote is about is an indication that the global economy is not working for everybody. It’s not working in the United States for everybody and it’s not working in the U.K. for everybody. When you see investors going to China and shutting down factories in this country and laying off, over a period of many years, millions of people, people are saying you know what, global economy may be great for some people but not for me.

Now let me say: There is truth is Sanders’s assessment. Obviously. And that truth is something that people like Cameron and Hillary Clinton need to do a better job of addressing. One of Clinton’s key challenges in this fall campaign will be to show that she is grappling with this anger and wants to ameliorate it.

By the way, I should note that I found Hillary Clinton’s response to be depressingly mealy-mouthed. Yes, she thinks she’s likely to be the next president, and as such, she might have to work with a Johnson government. I get that. But she couldn’t even say something gently reproachful like “While I’d have preferred the other outcome...”? Her statement lessens my confidence in her ability as president to make clear moral statements on the United States’s behalf.

But that said, at least we know which side she is really on. I’m not sure we know which side Bernie is on. Well, we need to find out, because Trump is our Brexit. He must not become the president. Yes, Bernie said as much last Friday. But he didn’t say it with any conviction. He didn’t look his MSNBC interlocutor in the eye; he just stared glumly down at the table. He spoke with all the commitment of a hostage reading a statement.

America needs more than that from him. If Donald Trump somehow wins in November, Clinton will go down in history as the Cameron. But if Sanders never goes much beyond the kind of half-hearted statement he made last Friday, then he will go down as the Corbyn, and he too will be disgraced for all time. He should, this week, avow forcefully that he will do all he humanly can to prevent what happened in the UK happening in America. And he should spend the entire fall doing the same. He doesn’t have to say a single nice word about her if he doesn’t want to. He just needs to tell his dead-enders why they must vote for Clinton to avert the catastrophe of President Trump.

Some might say the very premise of this column, tying Sanders and Corbyn together, is unfair. Maybe. If so, Bernie has plenty of time to prove me wrong.