Think of him as the comforting uncle, convincing the kids that a few ugly spats between Mom and Dad won't end in divorce.
It's an increasingly uncertain reassurance to make: Hillary Clinton and Bernie Sanders -- already locked in a primary battle longer than most Democrats expected -- have threatened to go nuclear as the primary season enters its back half.
This week saw Clinton step up her critiques of Sanders' policy proposals, deeming many unworkable in a real-world setting. In response, Sanders declared her unqualified for the job
, an assessment he spiritlessly walked back when it caused uproar among her backers and establishment Democrats.
The tack south was a long time coming, and carries obvious risks. Neither Clinton nor Sanders has much hope of winning November's general election unless the other's backers unite behind, or at the very least begrudgingly cast ballots for, the eventual nominee.
With entire chapters of his presidential legacy riding on who becomes the next president, no one has more stake in that happening than Obama. And as the Democrat that both Clinton and Sanders supporters can love, he stands the best shot at keeping the warring factions from inflicting mortal wounds.
Hence his push this week to convey solidarity among the discord.
"The cleavages inside the Democratic Party are not comparable to what we're seeing in the Republican Party right now," he said during a question and answer session with law students in Chicago on Thursday. "The argument inside the Democratic Party is a little bit more about means, less about ends."
He repeated that sentiment a day later during a high-dollar fundraiser in San Francisco, declaring the "two fine Democrats" running to replace him are displaying "tactical differences" but few gulfs on policy.
"There's not this big ideological divide among Democrats," he said.
That may sooth Democratic donors, but it doesn't necessarily reflect the scale of hostility that flared between Clinton and Sanders this week. Clinton, after an expectedly wide margin of defeat in Wisconsin, sharpened her blows on Sanders, declaring he "hadn't done his homework" on a variety of presidential issues.
"He'd been talking for more than a year about doing things that he obviously hadn't really studied or understood," she said on MSNBC.
Sanders took umbrage, declaring in response that Clinton wasn't qualified to become commander-in-chief. The resulting backlash drew only a halfhearted pullback.
"I have my doubts about what kind of president she would make," Sanders told
CNN's Jake Tapper.
That bickering prompted alarm among some party leaders, who could easily envision the Republican general election ads using Democrats' own words to cast doubt about the eventual nominee. The White House made no attempt to appeal to Sanders' side: "The President has said that Secretary Clinton comes to this race with more experience than any other non-Vice President in recent campaign history," spokesman Eric Schultz told reporters Thursday.
For the White House, ensuring the Democratic Party emerges from its nominating process intact has meant saying or doing little that would appear to favor Clinton, even as it remains obvious that Obama sees his former secretary of state as a more predictable caretaker of his legacy.
In demographic terms, the coalition that helped bring Obama into office has largely split between the two candidates: young people for Sanders, minorities for Clinton, and college-educated whites divided between the two. Even Obama has acknowledged that convincing those groups to vote could pose a challenge.
"When I'm traveling through Democratic circles I see, 'Oh, Mr. President, we love you so, and we're going to miss you so. And sometimes I'm not that excited about this election.' And I say, I have no patience for that,'" Obama told Democratic donors -- actresses Julia Roberts, Gwyneth Paltrow and Julia Louis-Dreyfus among them -- at the Bel-Air home of Walt Disney Studios Chairman Alan Horn on Thursday.
"I say to folks, we cannot be complacent, and we cannot be cynical, because the stakes are too high," he said.
But even as he sought to play down the acrimony among his two potential Democratic successors, Obama issued warnings to members of his party against becoming overly adherent to doctrine.
"The thing that Democrats have to guard against is going in the direction that the Republicans are much further along on, and that is this sense of we are just going to get our way, and if we don't, then we'll cannibalize our own and then kick them out and try again, and we narrow our viewpoints more and more until finally we stake out positions that are so extreme that they alienate the broad public," he said.
In front of donors in Los Angeles, Obama was more frank.
"We're also politicians. We care about getting elected. And we recognize that there are times in a big democracy like this that we've got to compromise," he said.