No incumbent president has participated in a primary debate since Ford. Democrats want to keep it that way.

President Joe Biden has successfully fended off calls from his opponents for him to participate in primary debates, a move that would be unprecedented in recent memory.

Democrats have so far opted to tune out the primary challenges levied against him, with the Democratic National Committee throwing its support behind Biden. And while some in the party have criticized the organization and Biden as "un-democratic" for presuming he’s the de facto nominee, there’s precedent in sitting it out: No incumbent president has participated in a primary debate since the first modern debate was held in 1948, even when presented with high-profile primary challengers.

As former President Donald Trump sought re-election in 2020, the Republican National Committee didn’t hold primary debates, nor did former President Barack Obama during his second bid. The same pattern can be traced as far back as Gerald Ford.

And Democrats today show no signs of changing course.

Biden’s candidacy is being challenged by two Democrats, Robert F. Kennedy Jr. and Marianne Williamson, who have remained critical of the DNC’s expected decision to unite behind the incumbent president.

Kennedy, Jr. has called the lack of debates "unfortunate."

Williamson, who ran in the open primary last cycle, has long accused the DNC of "rigging" the contest against her. In a recently published Newsweek op-ed titled "Debate Us, Mr. President," Williamson said Biden and the DNC were engaging in candidate suppression.

"The people have a right to hear from other candidates, with other ideas. This is not a time in our history for people to acquiesce to any form of control over things that will affect our lives and the lives of our children. Candidate suppression is a form of voter suppression, and the party that purports to be the champion of democracy should not be so wary of it in our own house," wrote Williamson. "The Democratic Party must allow President Biden to debate his opponents. The fate of our democracy is at stake, and only more democracy can save it."

Without top-level institutional support, name recognition or popularity among voters or a real appetite among party officials for a contested primary, neither Williamson nor Kennedy is likely to become the nominee.

The call to hold primary debates was even echoed by former CEO and co-founder of Twitter Jack Dorsey on Thursday after Biden after Biden tripped on a sandbag during the U.S. Air Force Academy graduation ceremonies, spurring some critics to question his fitness.

"Open the Democrat primaries and debates. This isn’t fair to anyone," Dorsey wrote on Twitter as he shared a video of the fall.

A portion of the public shares similar concerns, too. Americans said they thought Biden is not in good enough physical health to serve effectively as president by 62%-33%, according to the latest ABC News/Washington Post poll.

When asked by Politico in August 2022 about how they might deal with a primary challenge, DNC executive director Sam Cornale put it bluntly: "We're with Biden. Period."

The group also unanimously passed a resolution during their February winter meeting expressing its "full and complete support" for a second term for Biden and Vice President Kamala Harris.