Though former vice president Joe Biden has not entered the 2020 race, his supporters and advisers are already spinning.

Biden and others describe him as a lawmaker with a bipartisan approach, one who can work across the aisle to “get things done.” According to a New York Times report, one of the main reasons Biden wants to make the jump is because he believes that he can unite our divided country. “As a candidate, Mr. Biden would present Democrats with a clear alternative to the hard-charging liberals who now dominate the race and test the appeal of his old-school political profile at a moment the party is hungry for fresh faces but even hungrier to win,” the Times wrote.

Biden is unapologetic about his history working with Republican lawmakers, and often points to his Scranton, Pa., roots as proof that he understands the plight of America’s working-class voters far better than the current president, a billionaire born into a wealthy family in New York City.

But other candidates vying for the Oval Office are also emphasizing their ability to work with lawmakers across the aisle. They just haven’t been able to harness that message as effectively — yet.

Sen. Cory Booker (D-N.J.) told NPR on Thursday: “We are a nation of conscience, and I found partners on the other side of the aisle who agree with me on these issues. And we can build from there.” As a senator, he has prioritized criminal justice reform and helped push a sweeping plan that has gotten attention from both sides of the aisle.

Connecting with people from varied corners has been a major theme of Booker’s nascent campaign, and also a focus of his entire political career. When the former mayor was running for the Senate, The Washington Post’s Jason Horowitz wrote that Booker “rarely misses an opportunity to point out that he and [Republicans and former New Jersey Gov. Chris] Christie — two of the most talented and quick-on-their-feet politicians in the country — have worked together to bring development and jobs to Newark.”

Sen. Amy Klobuchar (D-Minn.) is also positioning herself as a practical unifier. Klobuchar has repeatedly won races in the Midwest with the help of Republicans. At a CNN town hall, she was upfront in her willingness to push back on ideas popular with the Democratic base, confirming her commitment to centrism.

On the issue of health care, she is open to “Medicare-for-all” in the future, a proposal popular with the Democratic base. But she said she’s also open to other approaches to the high costs of health care. The Post previously wrote about how nearly two-thirds of Klobuchar’s bills are co-sponsored with Republicans.

Even so, neither Booker nor Klobuchar gets the same attention as Biden. Surely, part of that is name recognition. Biden has been in public life for half a century, and served as vice president for two years. But it might be something deeper going on, too.

Bipartisanship is more likely to appeal to moderate and conservative Democrats. Nearly half of the Democrats who identify as moderate or conservative are white, according to reporting from 538. That group is less likely to believe in “barriers that make it harder for women to get ahead.” Nearly half agree with the idea that “blacks who can’t get ahead are mostly responsible for their own condition.” Another poll by Data for Progress found that “28 percent of white Democrats say individuals’ willpower, not discrimination, is the main reason for racial inequality.”

That data suggests that white, moderate Democrats might be less interested in electing a person of color or a woman than the party’s more liberal base. The same might be true for the white working-class voters drawn to Trump’s message in 2016. For them, Biden may appeal because of his background in a way that a female candidate or a person of color does not.

Of course, there’s another challenge for Biden, Booker and other moderates too — keeping the party’s liberal base excited. Because in a quest to win some of those who the Democrats left, he could risk losing some of those groups who have been most faithful.