Sen. Bernie Sanders of Vermont is dropping out of the 2020 presidential race, his campaign announced in an email to supporters on Wednesday.

His exit from the race makes former Vice President Joe Biden the presumptive Democratic nominee in the race against President Donald Trump.

Sanders built his campaign on transformative policies like universal healthcare, tuition-free public college, and the Green New Deal. He also secured early endorsements from influential progressive lawmakers.

Sanders hit the ground running with huge wins in a series of early primary and caucus states. But he failed to pick up momentum on Super Tuesday and in later contests, where former Vice President Joe Biden crushed him, particularly among black voters and older voters.

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Sen. Bernie Sanders of Vermont is dropping out of the 2020 presidential race, his campaign announced in an email to supporters on Wednesday.

Sanders' exit from the race makes former Vice President Joe Biden the presumptive Democratic nominee in the race against President Donald Trump.

In an address from his home in Burlington, Sanders said that his path to the nomination had become "virtually impossible" and that the country should stay focused on handling the coronavirus pandemic as it sweeps the nation.

"I cannot in good conscience continue to mount a campaign that cannot win and which would interfere with the important work ahead of all of us," he said.

Sanders congratulated Biden and called him a "very decent man," but he stopped short of officially endorsing Biden and said he would keep his name on the ballot in all the remaining primary races in an effort to collect enough delegates to influence the party platform.

Sanders hit the ground running with a series of wins in early primary and caucus states, but he failed to pick up momentum on Super Tuesday and subsequently lost delegate-rich states like Michigan and Florida to Biden, significantly narrowing his path to the nomination.

A veteran progressive lawmaker, Sanders built his campaign on calling for a "political revolution" and skewering the political establishment on both the left and the right. His 2020 presidential bid built on his 2016 primary race against Hillary Clinton, during which he established himself as the most prominent national voice for the populist, progressive left and an outspoken advocate for the working class.

Sanders has long championed policies like universal healthcare, tuition-free public college, and the Green New Deal, a plan to transition the US to 100% clean and renewable energy within the next decade.

The 78-year-old candidate gained steam with high-profile support from progressive lawmakers like Reps. Alexandria Ocasio-Cortez of New York, Ilhan Omar of Minnesota, and Rashida Tlaib of Michigan. Their endorsements came shortly after Sanders had a heart attack last fall and gave him momentum at an essential point in his campaign.

Sanders surged to the front of the Democratic pack with huge victories in Iowa, New Hampshire, and Nevada. But the Vermont senator lost steam after the South Carolina primary, in which he placed a distant second behind Biden, who captured the majority of the state's black voters.

Biden quickly overtook the progressive firebrand when he won 10 out of 14 states on Super Tuesday.

A national Morning Consult poll released the Friday after Super Tuesday found Biden crushing Sanders by 16 percentage points: More than half of the Democratic primary voters in the poll — 54% — said they would vote for Biden, while 38% said they would vote for Sanders.

Sanders pivoted most of his ground operation to crucial Midwestern states like Michigan following Super Tuesday as a last-ditch effort to resurrect his campaign. But the former vice president demolished Sanders in several states — including Michigan — on March 10.

Rep. Alexandria Ocasio-Cortez and Sanders at his campaign event in Durham, New Hampshire, on February 10. Joe Raedle/Getty Images

Sanders failed to boost youth turnout

Demographically, Michigan was tailor-made for a Sanders victory: It's a Midwestern state with a large blue-collar population that Sanders targeted with his populist message. The Vermont senator also clinched a narrow victory in Michigan in 2016 in a stunning upset over Clinton.

But Sanders suffered from low turnout among young voters in the 2020 campaign season.

Voters between the ages of 18 and 29 were a huge part of why he picked up momentum in 2016, and Sanders conceded that the turnout this time around wasn't enough to help him secure the Democratic nomination.

The drop-off in young-voter turnout on Super Tuesday was one of the primary reasons Sanders saw underwhelming results across the board.

"Have we been as successful as I would hope in bringing in young people in? And the answer is no," Sanders said in a press conference the day after Super Tuesday.

On March 10, Ocasio-Cortez appeared to concede Sanders' defeat in the primary during an Instagram livestream watched by about 8,000 people.

But she declared "generational" victory, arguing that the future of the party supported the kind of radical change she and Sanders were pushing for and had already won "enormous, decisive arguments on many, many issues."

Ocasio-Cortez urged her supporters not to lose hope in electoral politics and described cynicism as the "No. 1 enemy" of progressive change.

"Never, ever, ever let your heart turn black," she said.