Sources are telling the press that President Trump may not participate in Republican primary debates, but expect sitting out to become untenable with Governor DeSantis — Mr. Trump’s strongest challenger — poised to enter the race.

Alice Roosevelt said her father, President Theodore Roosevelt, “wants to be the bride at every wedding, the corpse at every funeral, and the baby at every christening.” Despite a similar craving for the spotlight, Mr. Trump hasn’t committed to trading barbs with fellow candidates. 

The New York Times reported earlier this month that Mr. Trump “is likely to skip at least one of the first two debates … according to five people who have discussed the matter with the former president.”

The first faceoff is set for Milwaukee in August, but it’s the second — hosted by the Ronald Reagan Presidential Library — that has drawn Mr. Trump’s strongest objection, with him telling aides that the venue has never invited him to an event.

The Times reported that Mr. Trump blames the snub on the chairman of the board of trustees for the library, Fred Ryan, who’s also the chief executive officer of the Washington Post, where his days appear numbered.

In December, a Post reporter, Annie Gowen, tweeted a video of Mr. Ryan leaving a town hall with employees about layoffs after saying it would not allow it to become “a grievance session,” earning the Washington Post Guild’s ire.

Mr. Trump may have hoped to claim a high-profile scalp in Mr. Ryan and only then attend the debate, commanding attention in the meantime while reminding primary voters that his large lead in the polls makes the primaries moot.

Mr. DeSantis’ entry into the fray, expected by the end of the month, upends Mr. Trump’s calculus. Now staying away won’t just deny challengers the boost in stature that comes from sharing a podium next to a president. It will also allow his chief rival the chance to dominate.

In any debate, a front-runner expects to have all the flak aimed at him, something best avoided, but with Mr. DeSantis on the stage and Mr. Trump at Mar-a-Lago, the former president would still take all those hits without the ability to fire back, making the Florida governor’s job a lot easier.

On the Democratic side, Mr. Biden is running the safe play, refusing to debate challengers, including Robert F. Kennedy Jr., who — thanks to the national Democratic Party leapfrogging South Carolina’s primary over New Hampshire’s — may be on the primary ballot while Mr. Biden is not. 

“Mr. Kennedy believes,” his campaign tells me in a statement, “the American people want and deserve debates. He continues to ask President Biden to join in free and open discussion of those range of important matters which concern all Americans.”

Since debates provide a unique window into candidates, Americans tend to cast a skeptical eye on those who avoid them. In 1992, the Democratic challenger, President Clinton, made hay of the incumbent, President George H. W. Bush, refusing to meet him on the hustings.

Mr. Clinton’s campaign drew attention to Mr. Bush’s absence — and undercut his record as a hero of World War II and victorious commander of the Gulf War — by deploying “Chicken George” operatives in bird costumes to heckle him.

Mr. Bush relented and faced Mr. Clinton and the independent H. Ross Perot. It was a move that could only hurt his candidacy and it did. One innocuous moment, when he checked his watch, was cast as him thinking he had places he’d rather be — and you’ll notice that candidates have ditched their timepieces ever since.

With Mr. Bush’s fate in mind, frontrunners have good reason to skip debates, but Mr. Trump craves TV ratings and refuses to let any attacks go unanswered, making the forums a temptation too great to resist. 

Since the former president also delights in upending political convention, the fact that staying away would be the same traditional play as Mr. Biden only increases the pressure he’ll feel to show.

Mr. Biden can rely on the power of incumbency to duck debates, but while Mr. Trump will play coy and build suspense, expect him to be there when the debate cameras roll, itching to fend off Mr. DeSantis — the baby and the bride rolled into one.