President Obama delivers remarks at a Hillary for America campaign event

WASHINGTON, DC - SEPTEMBER 13:  U.S. President Barack Obama departs the White House September 13, 2016 in Washington, DC. Obama is scheduled to travel to Pennsylvania to campaign for Democratic presidential candidate Hillary Clinton.  (Photo by Win McNamee/Getty Images)

WASHINGTON, DC - SEPTEMBER 13: U.S. President Barack Obama departs the White House September 13, 2016 in Washington, DC. Obama is scheduled to travel to Pennsylvania to campaign for Democratic presidential candidate Hillary Clinton. (Photo by Win McNamee/Getty Images)

PHILADELPHIA, Pa. — A cavalry of top White House Democrats — President Barack Obama, First Lady Michelle Obama, and Vice President Joe Biden — are arguing Hillary Clinton’s case this week as the Democratic nominee herself is convalescing from pneumonia and absent from the trail.

In Philadelphia Tuesday, the President makes his first solo campaign appearance of the year, hoping to convince his diverse array of backers that Clinton is worth their support.

The timing is opportune for a campaign eager both to spotlight its most popular surrogates and to move past a rocky patch. While Obama’s Philadelphia stop was planned well ahead of Clinton’s declaration that half of her rival’s supporters were “deplorable” and new worries about her transparency, the campaign hopes the President’s rally can at least provide a new storyline.

But even an appearance from Obama — whose approval rating reached a nearly eight-year high of 58% in an ABC/Washington Post poll Monday — won’t necessarily cure all of Clinton’s woes as the campaign enters its busiest stretch. The White House Monday said Obama would not be relegated to “damage control” for Clinton’s stumbles.

“I’ll leave it to them to make decisions about the most effective way to run their campaign,” said White House Press Secretary Josh Earnest. “The President is going to be in a mode tomorrow where he’s enthusiastically advocating for her election.”

The same applies for First Lady Michelle Obama, who makes her first campaign appearance for the Democratic nominee on Friday, promoting voter registration in Northern Virginia.

Loathe to engage directly in bitter partisan politics, the First Lady is more likely to spell out a more affirmative case for Clinton, according to aides.

Biden, who talked up Clinton during a stop in Charlotte on Monday, was more candid in his assessments, suggesting the candidate gets a “bum rap” when he was asked about her remarks casting some of Donald Trump’s supporters as deplorable.

“For every time she will say something where she says, ‘Well, maybe I should have said something different,’ think if they held Trump to that standard,” Biden said. “He’d be in trouble. He is in trouble.”

Obama’s busy schedule a factor

Even as Clinton is increasingly relying on Obama to carry her message to young and minority voters, the demands on the President’s time have largely forestalled an aggressive campaign schedule thus far.

Tuesday’s event in Philadelphia is only Obama’s second campaign stop for Clinton, after a joint appearance in Charlotte in July. Since then, Obama has helped raised money from Democratic donors, including during his vacation on Martha’s Vineyard last month, but he hasn’t headlined another rally until now.

White House officials point to a largely inflexible schedule of presidential commitments this month as a barrier to more frequent campaigning. While past presidents have faced similar obligations in the waning days of their tenures, Obama is more popular — and thus in higher demand as a campaigner than his most recent predecessors.

In August, Obama’s aides made a day-by-day assessment of the President’s commitments until election day, discovering few moments in September that would allow for rallies in key battleground states on behalf of Clinton.

Obama on Friday concluded a week-long swing through Asia, with stops on the front end in Nevada, Hawaii and Midway Island meant to burnish his environmental legacy.

Even Tuesday’s rally was restricted to a relatively close-by location. Obama had business at the White House Monday evening when he met with congressional leaders, and is due to meet Burmese State Counselor Aung San Suu Kyi in the Oval Office on Wednesday.

Obama’s four-day obligation at the United Nations General Assembly next week makes adding a campaign stop difficult before the end of the month. And while the campaign may arise implicitly during Obama’s final address to the gathering of world leaders — he’s expected to recap eight years of foreign policy, providing a contrast to Trump’s proposals — it’s hardly the setting for a fiery political throw-down.

Even in October, when the race will enter its frenzied sprint, the demands of the presidency mean an all-out, every-day-on-the-trail presence for Obama in unrealistic. Already the President’s schedule is filling up. The White House announced Monday that Italian Prime Minister Matteo Renzi would visit on October 18, a day-long affair that will stretch into a late State Dinner. A government funding battle also seems likely to occupy the President’s time this month

Many of the states that officials say Obama will target — including Florida, North Carolina, Iowa, Pennsylvania and Michigan — are easily accessible in a single day-trip on Air Force One, but would leave few moments for other business at the White House.

Given Obama’s sway among young and minority voters — populations historically difficult to get to the polls — there is pressure for the President to hit many states before their voting registration deadline passes. In Florida, Ohio, Michigan, and Pennsylvania, that means showing up before October 11.

“I think what is clear is that the President does have a lot of influence over a large number of voters that haven’t previously been regularly engaged in politics,” Earnest said Monday, adding the Clinton campaign is “hoping that the President will be helpful in making the case on their behalf to motivate voters to get registered and to participate on Election Day.”