Bernie’s most valuable surrogate, AOC. Photo: Joe Raedle/Getty Images

In a welcome sign for Democrats of party unity and an implied rebuke to “Bernie or Bust” voters, Alexandria Ocasio-Cortez told Seth Myers last night that she will support Joe Biden if he wins the Democratic presidential nomination:

I’ve said throughout this entire process that what is so important that we ultimately unite behind who that Democratic nominee is. I think it’s a two-way street. I’ve been concerned by some folks that say if Bernie’s the nominee, they won’t support him and the other way around.

Once again, AOC is proving herself to have extraordinary timing. Her endorsement of Bernie Sanders in October helped turn around what at the time look like a floundering campaign. At the time, it wasn’t all that clear she had made a smart move or that it would matter, as CNN reported:

Ocasio-Cortez’s endorsement was one of the most sought-after in progressive politics and, ultimately, she delivered it at one of the most uncertain times in Sanders’ long political career.

The New York Democrat told Sanders she would back him for president over the phone as he was lying in a hospital bed recovering from the heart attack that took him off the campaign trail for weeks, aides to both told CNN. When he fell ill in Las Vegas, Sanders’ campaign had been stalling in polls, as Warren pulled ahead and solidified her status among the front-runners.

Between then and Super Tuesday, Sanders had a very good run, with AOC serving as a key surrogate. It’s far too early to write off Sanders despite Joe Biden’s astonishing ascent, but not at all too early for people in his camp to make up their minds whether to weaponize threats of a general election defection to gain leverage — or to rule them out.

The decision by the country’s most influential young progresssive to pledge allegiance to the party she has sometimes discomfited is significant. And among other things, it should help convince Biden supporters and those who fear Bernie Sanders to reciprocate should this topsy-turvy nomination contest take another unexpected turn.