WASHINGTON (AP) — Former President Barack Obama has a delicate balance to strike: how to weigh the mounting opposition to President Joe Biden continuing his campaign with his loyalty to his former running mate.

In recent days, Obama has taken calls from congressional leaders, Democratic governors and key donors in which he has shared their unease about the prospect of Biden's campaign following his calamitous June 27 debate performance against his predecessor, Donald Trump.

But even as Obama has listened to Democrats' concerns, he has insisted that the decision to remain in the race is only for Biden to make, according to several people familiar with the matter who requested anonymity to discuss the private conversations.

Obama finds himself forging through the most delicate political moment for Democrats since former President Bill Clinton's impeachment, with much higher stakes. It's a moment that requires Obama to balance his role as a party elder and an honest broker for Democrats seeking advice while avoiding being seen as betraying his former vice president.

"President Obama has to and wants to play the role of statesman, above the political fray that former presidents have traditionally played," said Matt Bennett, who served as an aide to Vice President Al Gore and is now an executive vice president at the Democratic-leaning group Third Way. "He also wants to remain a credible sounding board for President Biden. If he takes a public position, that ends it."

Obama's relationship with Biden started as a marriage of political convenience when he picked the veteran Delaware senator in 2008 to be his vice president. When they served in the Senate, the two were not close.

It was a selection made in part to quiet concerns about Obama's relative inexperience and make white Democrats more comfortable with casting their ballots for the Black politician with less than four years in the Senate. The pragmatic relationship eventually evolved into a true partnership and friendship.

Julian Castro, who served as Housing and Urban Development secretary under Obama, said he wasn't privy to the private talks Obama has had about Biden, but called it crucial for "respected, trusted elders within the party" to speak clearly to Biden about the headwinds Democrats will face if he stays in the race.

"Whether it's President Obama, former President Clinton, Secretary Clinton, I think their most important role, at this point, is helping to ensure that we have a successful November," said Castro, who sought the Democratic presidential nomination against Biden in 2020 and has recently called on him to end his current candidacy.

Obama's concerns have surfaced as former House Speaker Nancy Pelosi presented polling to Biden that she argued shows he likely can't defeat Trump, while influential Democrats, including Senate Majority Leader Chuck Schumer and House Democratic Leader Hakeem Jeffries, have also sent signals of concern about Biden's political viability.

Meanwhile, among Democrats nationwide, nearly two-thirds say Biden should step aside and let his party nominate a different candidate, according to an AP-NORC Center for Public Affairs Research poll published this week. That sharply undercuts Biden's post-debate claim that "average Democrats" are still with him even if some "big names" are turning on him.

Biden is relying on longtime aides as he weighs whether to bow to pressure to step aside. He remains publicly insistent that he is the Democrat in the best position to beat Trump.

Campaign officials said Biden was even more committed to staying in the race as the calls for him to go mounted. But there was also time for Biden to reconsider - a brief opening seemingly being exploited by party leaders trying to plot his exit.

Obama has been taking more calls than he's been making on the matter and sees protecting Biden and his legacy as his top concern, according to the people familiar with his thinking, and largely has remained publicly silent about Biden's political tailspin.

In the calls with allies, the former president has been protective of Biden and does not believe taking a stronger stance — publicly or even privately — would be productive, according to people familiar with the matter.

The former president is also mindful of lingering tension in Biden's political circle over some in Obama's senior staff urging Biden when he was vice president to sit out the 2016 presidential race.

In his memoir "Promise Me, Dad," Biden wrote about having lunch in 2015 with Obama just months after his son Beau died of cancer in which they discussed the possibility of a 2016 run.

Obama, Biden recalled, asked if he was going to enter the race. Biden said that he told Obama he was not ready to make up his mind, but if he decided to jump into the race he would do it in time to be viable.

"The president was not encouraging," Biden wrote.

Obama also urged Biden as he was pondering the 2016 race to sit down with David Plouffe, an architect of Obama's winning 2008 campaign. Plouffe made it clear to Biden that he would face an uphill climb against Vermont Sen. Bernie Sanders and that election's eventual Democratic nominee, former Secretary of State Hillary Clinton.

Since last month's disastrous debate performance, more than 20 Democratic lawmakers have called on Biden to exit. He's also faced stinging criticism from prominent alumni of the Obama White House, including a group of senior aides that host the popular Pod Save America podcast and former Obama senior adviser and CNN analyst David Axelrod.

"There have always been two Joe Bidens. The empathetic, decent, big-hearted leader, forged in loss and grief, finding the good in his friends and opponents, in love with America, arms wide and open with space for everyone," Jon Lovett, a former Obama speechwriter and Pod Save America co-host, wrote on the social media site X last week. "And there's the blowhard with a chip on his shoulder, stubborn, something to prove, his fellow senators rolling their eyes as the finger wags harder and the stories get longer. Statesman and politician, hero and fool."

In an interview with BET this week, Biden insisted that he still has plenty of time to right his campaign. On Thursday, the campaign stated that Biden was committed to his reelection bid and would be the Democratic nominee.

Obama's concerns are surfacing at a moment when many Democrats believe that time is running out to get Biden out of the race with the Democratic National Convention just weeks away.

But Biden and Obama as they try to find their way through this moment seem flummoxed by the weight of legacy and tradition, said Edward Frantz, a presidential historian at the University of Indianapolis.

Obama, Frantz said, has shown himself a traditionalist in his nearly eight years out of office — largely maintaining the post-presidency tradition of his predecessors who have sought to avoid wading deeply into politics.

Biden, meanwhile, seems deeply aware that history often hasn't judged one-term presidencies kindly, Frantz said.

"Both Biden and Obama have legacy on their minds, and they have to juggle that along with duty to party and country," Frantz said. "To step away knowingly and willingly? Few have done so."

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AP writers Lisa Mascaro and Mike Balsamo contributed to this report.