(Bloomberg) -- Senator Bernie Sanders, the self-described democratic socialist who gained a national following when he challenged Hillary Clinton for the 2016 Democratic presidential nomination, raised more than $4 million on Tuesday from almost 150,000 individual donors after announcing another White House run, according to his campaign.

That haul makes Sanders, by far, the top fundraiser among 2020 Democratic candidates on day one of their presidential bids.

The Vermont independent, who again will seek to become the Democratic Party nominee, more than doubled the $1.5 million that Senator Kamala Harris raised from roughly 38,000 donors in the first 24 hours of her Jan. 21 presidential campaign launch. The California Democrat had been the biggest first-day fundraiser in the race so far.

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The donations on Tuesday came from every U.S. state and mirrored the average donation of $27 seen in 2016, the campaign said in a statement.

Sanders, 77, upended the Democratic establishment three years ago by siphoning support from the party’s liberal wing and young people, touching off a leftist movement that ushered progressives like freshman Representative Alexandria Ocasio-Cortez into office in the November midterm elections.

Despite coming up short against Clinton, Sanders won about 13 million votes in 2016 Democratic primaries and caucuses on a platform that criticized economic inequality and what he described as the greed of Wall Street.

The ability to raise money from small-dollar donors is key metric of viability in a growing Democratic presidential field that could near 20, where many of the front-runners have pledged to eschew corporate funding. Grassroots funding will also be one criteria by which candidates qualify for televised debates.

(Upwardly revises dollar amount in headline, first paragraph after Sanders campaign updated fundraising totals.)

--With assistance from Arit John.

To contact the reporter on this story: Kim Chipman in Chicago at kchipman@bloomberg.net

To contact the editors responsible for this story: Kasia Klimasinska at kklimasinska@bloomberg.net, Chelsea Mes, Derek Wallbank

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