Alexandria Ocasio-Cortez provides a badly-needed jolt to Bernie Sanders’ campaign while bypassing front-runner Elizabeth Warren and wounding her efforts to corral progressives behind her candidacy.

Ocasio-Cortez is a popular figure among younger liberal voters and she could have given a huge lift to Warren at a time when she’s rising in the polls and taking over Joe Biden’s spot as the candidate to beat in the Democratic contest.

But instead she sided with her fellow socialist Sanders even though he’s been supplanted by Warren in the polls, as liberal voters flock to her message of change.

Ocasio-Cortez is expected to formally endorse Sanders at a rally in New York this weekend. The Vermont senator on Tuesday also picked up the endorsement of another member of “The Squad,” Rep. Ilhan Omar (D-Minn.).

Ocasio-Cortez is one of the few endorsements that actually matter in the 2020 race but it’s still questionable whether she’ll be able to rescue Sanders’ campaign, which recently derailed while he recovered from a heart attack.

The endorsement comes at a time when Warren is starting to come under heavy fire from her Democratic opponents, who now view her as the biggest threat to win the nomination.

Tuesday night’s debate marked the first time that several of the Democratic candidates, and even the media, actually challenged Warren face to face in a coordinated attack. It could prove to be a turning point in the campaign.

Ocasio-Cortez’s endorsement of Sanders isn’t exactly a shock, since she worked on his 2016 campaign.

But it’s still a major coup for Sanders and a blow to Warren, who had also sought out AOC’s backing.

Ocasio-Cortez’s blessing is considered a major litmus test for Democratic candidates. She endorsed U.S. Sen. Edward Markey earlier this year, a huge victory for the Malden Democrat, who has been eagerly using it in fundraising pitches. Markey faces two primary opponents next year, U.S. Rep. Joseph Kennedy III and Shannon Liss-Riordan.

The AOC endorsement was especially timely for Markey because he has been seeking the support of younger voters and millennials.

Warren is similarly trying to position herself and court young voters even though she herself is 70 years old. An AOC endorsement could have been viewed as a sign that Democrats are getting behind Warren as the nominee.

But now she’ll have to watch Bernie soak up the adulation of AOC’s “squad.”