As President Joe Biden faces mounting questions about his age and mental acuity from within the Democratic Party — and increasing calls to step down from his reelection bid — Maryland Gov. Wes Moore is standing shoulder-to-shoulder with the president.

That effort continued Monday, with Moore joining Biden and campaign manager Jen O’Malley Dillon on a conference call with Biden supporters. According to reports, 400 people were on the call, during which Moore introduced the president.

And on Tuesday, Moore travels to Idaho for six days at the Sun Valley Conference, a gathering of rich and influential executives and investors known as “billionaire summer camp.” Last year, he raised money for Democratic governors there; his mission this year will almost certainly include answering questions about Biden, who has become an all-encompassing political story.

Moore has been charming crowds and talking to TV hosts on Biden’s behalf for more than a year, ever since he was among 50 named to a national advisory board for the campaign.

But that assignment has taken on new importance following Biden’s halting debate performance against Republican nominee Donald Trump in late June.

Biden appeared to struggle in the debate, looking frail and failing to forcefully make points against Trump. That led to private whispers and later public statements of doubt about Biden’s reelection prospects from within the Democratic Party.

But while some were raising concerns about Biden or calling on him to drop out, Moore has been among those circling the wagons to protect and promote the president.

With Moore as a surrogate, the Biden-Harris campaign team has a rising star in the party who is a polished promoter of the Democratic brand.

Moore’s team hasn’t answered questions about his Idaho schedule, but he’ll be among the kind of rich and powerful people who can make a difference in the presidential election with their campaign donations and influence.

It’s unclear what Moore’s role will be at Sun Valley this year — whether he’ll be trying to keep Biden supporters and donors on board, whether he’ll again raise money for Democratic governors, whether he’s going purely for his own benefit, or some combination. Neither Moore’s political team nor the Democratic Governors Association immediately responded to questions about Sun Valley on Monday.

This week’s pro-Biden efforts are part of a ramped-up level of surrogacy that has deployed Moore since the debate. Moore has hit the cable TV shows and the campaign trail to promote the president’s reelection bid.

When Democratic governors had a private audience with Biden last week, Moore emerged as one of the spokespeople for the group, offering reporters a robust endorsement of the president’s reelection bid.

“The president has always had our backs,” Moore said outside the White House. “We’re going to have his back as well.”

Moore said Biden is “in this to win this” and that he’s confident Biden can win reelection in November.

“The president is our nominee. The president is our party leader,” Moore said.

Moore followed that pronouncement up with multiple pro-Biden emails to supporters, including one asking supporters to make a donation that would be split between the governor’s campaign and the president’s campaign.

Earlier — just a couple days after the Biden-Trump debate — Moore took a weekend campaign swing through Wisconsin for Biden, shaking hands and eating ice cream.

“If we stand divided, we’re not going to win. But if we stand united, there’s no way we can lose,” Moore told a TV reporter in Kenosha, though he acknowledged Biden “had a tough debate.”

Moore has relayed the message close to home, too. On Monday, the governor called into “The T.J. Smith Show” on Baltimore’s WBAL NewsRadio, declaring: “I am in deep support of President Biden. I know what kind of partner President Biden has been to the state of Maryland.”

Leaders of the Maryland Republican Party are not impressed with Moore’s travel schedule on behalf of the Biden-Harris campaign. Following the Wisconsin trip, the party issued a statement saying that Moore has a duty to focus on the state’s problems.

“Just a little over a year into his term, he has made the choice to shirk that responsibility, in favor of boosting the presidential campaign of a candidate that is visibly in cognitive decline, and raising his national profile for a future when that candidate is out of the way,” party Chairwoman Nicole Beus Harris said in the statement.

Beus Harris says that Moore’s long-term goal is “getting out of Maryland and running for President.”