Joe Biden speaks in Philadelphia after more crucial wins against Bernie Sanders. Photo: Mark Makela/Getty Images

The big question for Bernie Sanders after Tuesday night's losses: Is there a path back to the Democratic nomination, or is Joe Biden's trajectory unstoppable?

The state of play: Notably, Sanders did not comment on the results. Pressure ramped up on him to concede and Biden carefully began to turn his remarks to the general election after extending his delegate lead in "Super Tuesday 2," with wins in Michigan, Mississippi, Missouri and Idaho.

Biden, speaking in Philadelphia, made a measured pivot, saying he takes "nothing for granted" but that "this campaign is taking off" — and that he will speak to Americans later this week about addressing the coronavirus threat.

  • He thanked Sanders — and Sanders' supporters — for their "tireless energy" and "passion."
  • Biden also invited in new backers, saying, "We need you, we want you and there's a place in our campaign for each of you."
  • He also acknowledged "so many" former primary rivals who've endorsed him: "We're bringing this party together. That's what we have to do."
Chart: Naema Ahmed/Axios

Between the lines: In Tuesday's contests, Biden bested Sanders by wide margins with African American voters, according to a Washington Post analysis of exit polling data.

  • Health care was the top issue for voters in Michigan, Missouri and Mississippi.
  • In Mississippi, Biden won decisively even among voters who prefer replacing private health insurance with a single government plan for everyone, and who identify as "very liberal."
  • Biden led Sanders among voters, including white voters, without a college degree in Michigan.

Michigan was a huge loss for Sanders that his campaign worked hard to avoid.

  • Sanders last week scrapped an event in Mississippi to spend more time there, adding last-minute events throughout the state and hit the pavement hard.
  • He secured the endorsement of Rev. Jesse Jackson and campaigned with Rep. Rashida Tlaib in her home state.
  • He escalated attacks against Biden — both on his record and the idea that he is the "establishment." Some of his supporters even pushed #WheresBiden on Twitter and questioned his mental acuity.

What they're saying: "The math says 'Joe is our prohibitive nominee.' We need to bring the party together. We need to start working on defeating Donald Trump in the fall," Biden's former rival Andrew Yang, who backed Sanders in 2016, said on CNN Tuesday night.

  • "The progressive world wants a Bernie vs. Biden debate, as should all Democratic voters," said Adam Green, co-founder of the Progressive Change Campaign Committee. It may not change the outcome, he said, but could compel Biden to commit to popular progressive positions and test his ability to withstand the sort of scrutiny he'd face on stage with Trump.
  • "They didn’t fall in love with Joe. They fell in line," Detroit native, strategist and former newsman Ron Fournier tells Axios.
  • In 2016, many Democratic voters in Michigan considered Trump an "unqualified jerk but they didn't think he stood a chance to be president," Fournier said, and wanted to "send a message" to Hillary Clinton. This time around, Democrats are "desperate to unite and win" and "Biden is the last non-socialist standing."

What's next: Sanders could still try to take Biden down in a televised debate on Sunday, but it would take a massive upheaval to change the course of the contest now.

  • Coronavirus fears have begun to halt the sort of large rallies that have been staples of Sanders' campaign, after Biden and Sanders both cancelled rallies in Ohio on Tuesday at the request of state officials concerned about spreading infection.
  • Biden is poised to dominate in the March 17 contests that include Florida, the nation's third most-populous state.

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