Opinion | Bernie Sanders Romps in Nevada. Is He Unstoppable?

So here are three lessons for PleaseNotBernie from the wreckage that was NeverTrump:

You need candidates who aren’t actually winning primaries to drop out.

The fatal conceit of establishment politicians facing an insurgency is that because the insurgent has obvious weaknesses, they should hang around and hang around, piling up third-place finishes and minor delegate hauls, in the hopes of gaining … something. What they are actually likely to gain is blame, irrelevance, or both; just ask those noted influencers Jeb Bush and John Kasich.

So if you are, say, Amy Klobuchar, the fact that you have a solid case for your own electability is not a reason to stick around for Super Tuesday if you finish behind Pete Buttigieg in South Carolina as well as in Nevada. If you’re Buttigieg, your strong Iowan and New Hampshire performances aren’t a reason to stay in if it’s clear you can’t compete nationally with Michael Bloomberg and Joe Biden. If you’re Biden, if you lose South Carolina, you should drop out the next day. And so on.

None of this means that simply consolidating the field will stop Bernie; he might well win a head-to-head race, too. But giving him five or six opponents in every contest makes the solidity of his core support an insurmountable advantage. And if you can narrow the field, the second lesson comes into play:

Against an unconventional front-runner, unconventional measures are required.

In the case of Trump, the person most willing to think this way was Ted Cruz, who made a serious bid to induce Marco Rubio to join him in an anti-Trump unity ticket. Would this have ultimately worked? Quite possibly not, but it was a brighter idea than the path that Rubio ultimately took — passionately bemoaning Trump’s ascent but refusing to gamble boldly in response.

There isn’t an obvious unity ticket equivalent for the non-Sanders Democrats, but the dynamic between Bloomberg, Biden and Buttigieg is worth watching. They are all positioned as moderate alternatives to the Sanders revolution, and after South Carolina and Super Tuesday one of them may look a lot more viable than the others. In which case two of the B’s swiftly dropping out and just as swiftly campaigning and fund-raising for (or simply funding, in Bloomberg’s case) the third might be the only chance at a not-Sanders consolidation. And that chance is worth taking because of the third lesson:

You probably can’t stop a plurality candidate at a contested convention.

And that’s especially true if he has a clear delegate lead. I spent the early months of 2016 arguing otherwise, but the party system I was defending is pretty obviously dead. There’s little stomach among party officialdom to work against a candidate who wins the most primary votes, and voters themselves are unlikely to sustain rival candidacies if they’re clearly just playing for a brokered convention.