Vermont Senator Bernie Sanders has a critical mission on Tuesday: beating former Vice President Joe Biden in Michigan.

On a day when 352 of the remaining delegates in the Democratic presidential primary will be awarded, Michigan is the biggest prize, allocating 125 pledged delegates. But that’s not the only reason the Midwest state is crucial for Sanders. Losing in a state that Sanders has emphasized in the days since Super Tuesday would be a symbolic setback, especially since Sanders upset Hillary Clinton in Michigan in 2016; Clinton then went on to lose it to Donald Trump. To win the Democratic nomination, Sanders will need to rally the kind of white working-class voters that comprise a large percentage of Michigan Democrats.

“If Bernie Sanders doesn’t win Michigan, it is a critical sign that his campaign is flailing,” says TJ Bucholz, a Michigan Democratic strategist unaffiliated with any of the 2020 presidential campaigns.

The odds don’t look great for Sanders, according to recent surveys. Multiple polls conducted in recent days have pegged Biden as a clear double-digit favorite. (Polling in 2016 showed Clinton leading Sanders.) Bucholz noted that Biden, who served as Vice President under Barack Obama, is also often associated with the Obama Administration’s auto bailout, a critically important rescue for a state that has long been the epicenter of the U.S. auto industry.

Michigan has taken on increased importance for Sanders since Super Tuesday, when Biden took the delegate lead and re-established himself as the favorite to become the party’s presidential nominee. Rather than spend time in Mississippi as originally planned, Sanders’ campaign cancelled a trip there and added events in Michigan. If skipping Mississippi sends a message that he has all but ceded the South to Biden, then Sanders’ ability to demonstrate that he can do well elsewhere becomes even more important. “Right now, our focus is here in Michigan, where we think we have the agenda that can win this state,” he told CNN’s State of the Union this weekend.

Sanders is pulling out all the stops. Rep. Alexandria Ocasio-Cortez, his highest-profile surrogate, campaigned for him in the state over the weekend. Civil rights leader Rev. Jesse Jackson, Sr. endorsed him and spoke on his behalf. Michigan’s majority-black cities, like Detroit and Flint, have been a focal point, with Sanders scheduling a town hall in Flint over the weekend. Black voters launched Biden to victory in South Carolina and on Super Tuesday, highlighting how critical their support will be for whoever ends up the nominee. So far Sanders’ support among African Americans has been lacking.

“We need to expand our base of support and make sure our message is getting through,” says Rep. Ro Khanna, a national co-chair for Sanders’ campaign. The focus, Khanna says, should be improving outreach to black and older voters, constituencies Sanders has struggled to win. “I think we have to make the case of electability,” he adds.

While Sanders was reportedly prepared to give remarks in Flint that would “directly address the African American community and make the case for why black voters should support him over Vice President Biden,” he gave a half-hour version of his regular stump speech instead. A Sanders aide reportedly said that after speaking with participants backstage, Sanders had decided to let the people of color on the panel speak to those issues. “He does not have those experiences,” Mike Casca, Sanders’ communications director, told reporters. “He is a white Jewish man.”

Meanwhile, Sanders is trying to make this a primary about issues, like health care and trade. Michigan is a “canary in the coal mine around sort of the same type of policies that Bernie’s has been championing,” such as trade, says Branden Snyder, executive director of Detroit Action, a grassroots organization focused on racial and economic justice issues that has endorsed Sanders.

While Sanders has argued high turnout—especially new voters—will be the key to his success, Super Tuesday suggested the strategy may not be working. It was Biden, not Sanders, who benefited from increased voter turnout on Tuesday.

“The progressive movement is at a moment where we really have to think about, how do we create a message that appeals both to an expanding electorate and talks to swing voters?” says Monica Klein, a progressive strategist. There are parts of Sanders’ platform, Klein said, that appeal broadly across the Democratic Party, like higher wages. “And I don’t think that one necessarily needs to negate the other, but I do think what Bernie obviously has realized, what his team has realized, is that they can’t just be feeding the base, that they also need to be speaking to more moderate voters, to African-American older voters.”

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Write to Lissandra Villa at lissandra.villa@time.com.