Alexandria Ocasio-Cortez has refused to endorse Bernie Sanders for the 2020 Democratic nomination, despite working on the senator’s first presidential campaign.

A spokesperson for Ms Ocasio-Cortez, like Mr Sanders a self-described democratic socialist, refused to comment directly on the 77-year-old’s Tuesday announcement he is running for a second time.

“We’re excited to see so many progressives in the race,” spokesperson Corbin Trent said. “We’re not thinking at all about the next election.”

Any endorsement by Ms Ocasio-Cortez is likely to be influential on the outcome of the race, thanks to her massive support among the grassroots of the party.

But the 29-year-old, a congresswoman for New York, is unlikely to offer an endorsement before her state's Democratic primary next year, and may even permanently withhold any explicit support for a single candidate.

But even without Ms Ocasio-Cortez's support, Mr Sanders’ team is setting the bar for victory in the crowded 2020 Democratic field will be relatively low.

Along with an extraordinary small-dollar fundraising operation, it suggests Mr Sanders is poised to maintain his status as a political force in 2020 whether most of his party wants him to or not.

He is showing no desire to change his approach to broaden his appeal, as is sometimes the case with ambitious second-time candidates.

Nina Turner, president of Our Revolution, the political arm of Sanders’ expansive network, said the 2020 campaign “is really about him finishing what he started”.

In a sign of the scale of the support, Mr Sanders raised more than $4m (£3.1m) from nearly 150,000 individual donors in the first 12 hours after launching his bid, his campaign said.

Previously, the biggest first-day fundraiser in the race had been Kamala Harris, who raised $1.5m (£1.2m) in the first 24 hours of her campaign.

Even before Tuesday’s fundraising haul, however, Mr Sanders had more cash in the bank than any of his competitors. He entered the contest with roughly $15m (£11.5m) to devote to his 2020 campaign, a combination of his senate campaign fund and what is left over from his 2016 presidential bid.

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“Bernie Sanders is the frontrunner,” tweeted former Hillary Clinton staffer Zac Petkanas. “Let’s see how he likes it.”

Additional reporting by AP