President Biden, facing a political crisis in which some of his Democratic allies are asking him to be more unscripted in order to demonstrate his ability to win over voters, instead stuck to his script on Sunday, reading from notes for an address to a church congregation that lasted roughly seven minutes.

At a worship service at one of Philadelphia’s biggest Black churches, Mr. Biden — speaking without a teleprompter, which he uses in most of his public remarks — sought to reassure a group of voters who helped him win the White House in 2020 that he is still capable of beating former President Donald J. Trump.

“The joy cometh in the morning,” Mr. Biden told several hundred people at Mount Airy Church of God in Christ, where a visit has become something of a rite for Democrats. “You’ve never given up. In my life, and as your president, I’ve tried to walk my faith.”

Mr. Biden is at a tension point in his campaign, with his advisers seeking to keep his appearances tight and other Democratic allies wanting him to be more freewheeling to show he can respond in real time to events.

“They don’t need scripted remarks,” said Steve Sisolak, the Democratic former governor of Nevada. “He needs to show people that he can do it on the spot and answer questions — tough questions — and be out there with voters.”

The president did spend far more time meeting voters at the church and at two events later on Sunday than he has in recent weeks on the campaign trail. Ammar Moussa, a spokesman for the Biden campaign, said Mr. Biden did exactly what he needed to.

“Here’s what happened on the ground today: Joe Biden campaigned with the heart of the Democratic Party and met with voters and elected officials across a key battleground state,” Mr. Moussa said in a statement. “This is the work that wins elections: focusing squarely on engaging and reaching real voters where they are. You’ll see him do that in Michigan this week, Nevada next week, and all of the battlegrounds between now and November.”

With his every movement and utterance under intense scrutiny, Mr. Biden avoided errors in his brief speech. But some Democrats are asking for far more than a gaffe-free morning.

Senator Chris Murphy of Connecticut, appearing on CNN on Sunday, pushed the president to “do a town hall, do a press conference — show the country he is still the old Joe Biden.”

Still, unscripted appearances come with risks, especially after Mr. Biden’s disjointed 22-minute interview with ABC News failed to calm Democratic nerves. He also stumbled during two radio interviews, even though Biden campaign aides had provided the hosts with the questions, a breach of journalistic ethics that led one of the hosts to leave her station.

And although Mr. Biden’s remarks at the church were short, his thoughts occasionally seemed jumbled and his voice could sometimes be hard to hear.

“I know I’m going to be inclined to go on longer than I should here, so I’m not going to,” Mr. Biden said before wrapping up.

His likely opponent in November, Mr. Trump, has no such qualms about talking.

At his marathon rallies, Mr. Trump, using a teleprompter but often going on riffs without it, speaks for upward of 90 minutes. He tells outrageous lies. He employs hateful language. He mixes up names, dates and places.

But the bombastic former president — who at 78 is three years younger than Mr. Biden and with his heavyset frame appears far more physically imposing — does it all with prodigious stamina. Polls show that voters have fewer concerns about Mr. Trump’s age than Mr. Biden’s.

After Mr. Biden attended church, top House Democrats gathered privately to discuss his candidacy, with several senior members suggesting he step aside.

More publicly, Democrats asked him to demonstrate that he could campaign at a high level.

Senator Angus King, an independent from Maine who caucuses with Democrats, said in a statement issued by his spokesman that Mr. Biden should participate in more “unscripted interviews and direct interactions with voters.”

The president will hold a solo news conference after a N.A.T.O. summit on Thursday — which to some Democrats may feel like an eternity, with every day bringing more Biden allies suggesting in public or private that he drop out.

Mr. Biden has insisted he will not do so, saying in his Friday interview that only the “Lord Almighty” could force him to step aside.

He also eschewed his teleprompter at two other events on Sunday. He spoke for about seven minutes at one of his campaign’s offices in Philadelphia, assuring the audience that his alter-ego, Dark Brandon, was “coming back.” And he addressed supporters at a union event outside Harrisburg for another six minutes.

Before Mr. Biden spoke at the Philadelphia church, one congregant, Rachel Hooks, offered a prayer from the stage that did not shy away from the doubts swirling around his candidacy.

“Touch his mind, O God, his body; rejuvenate him and his spirit, O God — bless him and give him direction,” Ms. Hooks said, echoing a similar plea for mental and physical strength she also offered for members of law enforcement.

During his career, the president has frequently turned to Black faith communities both to offer support during community tragedy and to seek it when he is struggling politically.

Black voters make up a key segment of Mr. Biden’s coalition, although polls show their enthusiasm for his candidacy has dipped. Still, they have higher opinions of the president’s performance than other groups and are less likely to think he should drop out, according to a New York Times/Siena College survey conducted after the debate.

“Let him know we’re with him, hallelujah,” one woman shouted out from the audience as Mr. Biden walked onstage and a choir sang.

In an energetic sermon, Bishop J. Louis Felton pointed to Mr. Biden’s well-documented childhood stutter and said his style of speaking should not be held against him.

After the service, Mr. Biden mingled with congregants in the church sanctuary, shaking hands and taking photos for more than 30 minutes.

Stacia Parker, 57, a longtime member of the Mount Airy church, said she thanked Mr. Biden for forgiving $117,000 worth of her student loans. She said she found him cogent and compelling, both onstage and up close in person.

“We don’t kick you when you’re down,” Ms. Parker said, showing off a selfie that the president snapped on her phone with her seven-year-old granddaughter.

Reporting was contributed by Annie Karni, Luke Broadwater, Michael Gold and Maggie Astor.