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The supporters of Elizabeth Warren and Bernie Sanders, the two progressive Democratic presidential candidates, have been notoriously unfriendly to one another ever since the candidates’ icy encounter following a January debate revealed growing cracks in the former allies’ relationship. Their disagreement centered on Warren reminding Sanders of comments she says he made about a woman’s unelectability against Trump. Sanders denied the comments and, after the debate was over, Warren was caught on tape accusing Sanders of calling her a liar. Sanders supporters flooded Warren’s twitter replies with snake emojis, and Warren supporters doubled down on their rebukes of so-called “Bernie Bros.”

The animosity has continued during the weeks preceding the Super Tuesday showdown and has shown no signs of slowing down. But with the unexpected resurgence of former Vice President Joe Biden’s campaign and the coalescing of support from mainstream Democrats around him, Rep. Alexandria Ocasio-Cortez (D-N.Y.) and other progressive elected officials are urging unity among progressives ahead of the Democratic presidential nomination.

The movement started on Monday, with a tweet from a national surrogate for Sanders’ campaign.

im a Sanders supporter that builds with Warren supporters. — phillip agnew (@iPhilSomething) March 2, 2020

Then New York’s state Sen. Mike Gianaris, a Sanders supporter, tweeted his solidarity with Warren supporters, adding the hashtag #BuildTogether.

I’m a Bernie supporter who builds with Warren supporters. Let’s do this @Biaggi4NY. #BuildTogether Pass it along — Sen. Mike Gianaris (@SenGianaris) March 2, 2020

Other progressives were quick to join in. New York state Sen. Alessandra Biaggi chimed in from the Warren camp:

I’m a Warren supporter who builds with Bernie supporters. Let’s do this @JuliaCarmel__ 💙 #BuildTogether Pass it on! https://t.co/QdgX6mfFRD — Alessandra Biaggi (@Biaggi4NY) March 2, 2020

And Ocasio-Cortez took the conversation to the national stage:

I’m a Bernie supporter who builds with Warren supporters. It’s how we got a top-to-bottom progressive ballot sweep in NY14. Throughout it all, Alessandra & I do town halls &collect signatures together to get each other on the ballot. We’ve got each other’s back.💜#BuildTogether https://t.co/G0QZVbbcDR — Alexandria Ocasio-Cortez (@AOC) March 3, 2020

Meanwhile, former 2020 candidates Minnesota Sen. Amy Klobuchar, South Bend Mayor Pete Buttigieg, and former Texas Rep. Beto O’Rourke all endorsed Biden at a campaign event in Texas on Monday night. As the moderate coalition for the former vice president strengthens, progressives will have new urgency to jettison the snake emojis and rally around an alternative Democrat.