Presumptive Democratic nominee Joe Biden is facing an uphill battle as the general election takes shape: turning out Sanders supporters and preventing a “Never Biden” movement akin to “Never Trump” and “Never Hillary” factions that determined the election in 2016.

In Michigan, a must-win state for Democrats in 2020, just 2 out of 5 Sen. Bernie Sanders (I-Vt.) backers say they will vote for the Democratic candidate in November, regardless of nominee, according to exit polls reviewed by Politico.

The outlet also claimed that four out of five voters said they would be dissatisfied with Biden as the standard-bearer for the Democratic party platform.

Biden’s campaign has been making active efforts to reach out to the progressive wing of the party, in some cases directly working with Sanders’ and closest allies on the campaign.

In the two weeks leading up to the Democratic socialist’s announcement that he was withdrawing from the race, Biden and his allies were in quiet contact with Sanders’ team, trying to find common ground on policy in an effort to unite the party, according to the New York Times.

Conversations were conducted over “intense” conference calls, The Times reports, and topics included health care and climate change among other policy matters.

Jeff Weaver, Sanders’ top political adviser, and Faiz Shakir, his campaign manager, negotiated on the candidate’s behalf. Anita Dunn and Ron Klain, two longtime Biden surrogates, represented the Democratic frontrunner.

Speaking to donors last week during a virtual fundraiser, Biden mentioned that he would be expanding his climate change platform in an effort to reach out to progressive groups.

In mid-March, he announced he was adopting proposals from both Sanders and Sen. Elizabeth Warren’s (D-Mass) campaigns.

From Sanders, Biden said he would be taking on his College-for-all plan, making public colleges and universities free for families making under $125,000. From Warren, the presumptive nominee courted her supporters with an official endorsement of her bankruptcy proposal.

The two factions of struggle for Biden are younger voters and the Latino community, demographics that swung heavily for Sanders in both the 2016 and 2020 Democratic primaries.

Sanders has not yet endorsed the former vice president, making it even harder for Biden to urge his supporters to join his team. The Vermont senator has said previously, however, that he would do everything in his power to stop President Trump from winning reelection.