Defenders of Sanders correctly point out that we live in a more polarized and partisan era, and that anti-Trump feeling will surely put a political floor under Sanders well north of McGovern’s 37.5 percent of the vote. And that’s probably true. It’s hard to see Sanders losing California or New York, as McGovern did.

But in an important way, Sanders represents an even greater danger to Democrats than McGovern did. McGovern ran in an age of ticket-splitting. In that same election where McGovern did so disastrously, Democrats lost only 12 seats in the House. They actually gained two in the Senate and also won a governorship.

That pattern will not repeat itself in 2020. If Sanders loses badly as moderate voters swing away from Democrats, he will take with him a big clutch of House Democrats and Democratic Senate hopefuls. It will be a loss up and down the ticket, a loss that could not only reelect Trump, but also enable him, by preserving his elected bodyguard in the Senate and restoring his majority in the House. The question to weigh before Super Tuesday is thus not only Sanders versus Biden or Sanders versus Bloomberg. It is whether you prefer Speaker Pelosi or Speaker McCarthy, and Chairman Schiff or Chairman Nunes. The hopes of congressional Democrats hang in the balance in the fateful week ahead.