President Obama meets with Pope Francis at the Vatican in 2014. When Francis arrives in the United States, he will get an airport welcome that few world leaders get: a plane-side greeting from the president and first lady. (Pablo Martinez Monsivais/AP)

Vice President Biden offered a glimpse earlier this week into how the White House, deeply frustrated by the gridlocked and bitter state of American politics, has come to view Pope Francis’s visit to the United States.

“The most popular man in the world is about to come to the United States of America,” Biden told a group of Hispanic Americans who had gathered at his residence. “The single most popular man in the world.”

It’s not simply Francis’s popularity that enthralls the White House but also his ability to transcend the rancor of U.S. politics in a way that consistently has eluded President Obama.

The big question for Obama and his advisers is whether the pope’s soaring popularity can ­ever-so-slightly shift the ground on some issues crucial to the White House and provide openings for the president in his waning months in office.

The pope has taken progressive positions — sometimes to the left of Obama, and well outside the mainstream of American political discourse — on issues such as criminal-justice reform, immigration and economic inequality. Earlier this year, he suggested that global warming, driven by overconsumption, materialism and greed, threatened to turn the Earth into “an immense pile of filth.”

Yet he remains beloved by Republicans, including House Speaker John A. Boehner (R-Ohio), who invited Francis to address a joint meeting of Congress next week.

“If Obama said some of the things that Francis says, he’d be labeled a Trotsky-ite,” said Candida Moss, a theology professor at the University of Notre Dame. “It must be amazing for him to be able to say that I am just to the right of Pope Francis on this issue.”

Obama and Francis haven’t spent much time together over the two years of Francis’s papacy. The two leaders sat together at Francis’s spare Vatican desk for about 45 minutes last year, when Obama said, “The bulk of the time was spent discussing two central concerns” — the plight of “the poor, the marginalized and growing inequality” and the challenge of war in the world today.

Francis, meanwhile, has shown little interest in spending long hours, during his first trip to the United States, in meetings with Obama or other senior White House officials.

“We think that we are the center of the world here in Washington,” said John Carr, director of the Initiative on Catholic Social Thought and Public Life at Georgetown University. “We aren’t the center of Pope Francis’s world.”

And that may provide the White House its best opportunity to open the debate on a series of hopelessly gridlocked issues that are at the core of Obama’s agenda. The pope’s power hasn’t come so much from his words — often he will toss aside his prepared remarks — but from his actions. Francis has said he doesn’t know how to use a computer and has never owned a cellphone. “I’m a dinosaur,” he said in 2013.

But he has an innate sense for the dramatic gesture that gets played and replayed on the Internet. Following his first Easter Mass at St. Peter’s Square, Francis left his popemobile and descended into the crowd to lift up and kiss a boy with cerebral palsy. The video of Dominic Gondreau and the pope played for most of the day on Fox News and CNN and was featured on the ABC and NBC nightly newscasts.

On a visit to Sri Lanka earlier this year, Francis dropped his planned schedule after a chance meeting at the airport with a ­Buddhist monk who invited him to his temple. The pope, unlike his predecessor, regularly poses for selfies with newly married couples and babies.

Those viral moments have defined Francis for many American Catholics who, in many cases, have only passing knowledge of his positions on climate change and poverty. A recent survey by the Associated Press found that only 40 percent of American Catholics were aware of the pope’s encyclical on climate change and that just 23 percent said that they had heard about it from their priests at Mass.

The flood of media coverage on the pope’s visit will probably give Americans a broader and deeper understanding of the pope’s message. But White House officials said that the pope’s trip probably won’t be defined by his speech to Congress, his appearance at the United Nations or his meeting with Obama at the White House.

Most Americans’ impression of Francis will be shaped by his improvised and tweetable moments.

The first of those could come when the pope’s plane arrives in the United States from Cuba and is greeted by Obama. Republican critics have lambasted Obama’s decision to restore diplomatic ties with a Castro government that continues to use brutal tactics to stifle political dissent.

The image of the pope’s plane landing in the United States after a visit to the island nation has the potential to shift the debate on the morality of the Obama administration’s decision to depart from a five-decades-old policy of isolation, White House officials said.

In Philadelphia, Francis will meet with 100 inmates and their families at the city’s largest prison, a potential boon to Obama’s push for criminal-justice reform.

Obama has made the case that imprisoning low-level drug dealers for decades is unfair and excessively costly. “Every year, we spend $80 billion to keep folks incarcerated — $80 billion,” Obama said earlier this year in a speech to the NAACP. For Francis, who has called life sentences a “hidden death penalty” and decried solitary confinement as inhumane, criminal-justice reform is exclusively a moral issue.

“Pope Francis is invested in the morality of the species, and that gives him tremendous power,” Moss said. “He has nothing to gain out of it.”

The most striking moment of the pope’s trip could be when he delivers Sunday Mass in Spanish to an audience that will probably consist of thousands of immigrants from Central and South America.

The visit also offers the president an opportunity to renew the progressive Catholic ties he first developed as a community organizer in Chicago. In the past, he has talked about how his “heart and mind were touched” by Cardinal Joseph Bernardin, the archbishop of Chicago until he died in 1996. Obama’s relationship with the church frayed over contraception requirements in the Affordable Care Act and over same-sex marriage.

The president “does feel stung by the fact that the official Catholic Church, the institutional church in the United States, has not warmed to him,” said Stephen Schneck, who co-chaired Catholics for Obama during the 2012 campaign. “He feels that particularly.”

Earlier this month, Biden gathered about a dozen Catholic leaders and a few of his aides at his residence to talk about Francis’s upcoming visit. The discussion lasted for nearly two hours. In a sign of his high hopes for the visit, the vice president boasted that he had read every word of the pope’s 184-page encyclical on climate change.

To many in the White House, including Biden, Francis’s message of outreach to those on society’s margins offers a quiet but powerful rejoinder to Republican front-runner Donald Trump’s calls for a border wall and a tougher policy against immigrants.

A few days after his meeting with Catholic leaders, Biden was touting the pope’s message of empathy at a Hispanic Heritage Day celebration at his home. “That’s where people are,” Biden told the crowd. “That’s what they’re looking for.”

Now, the questions for the White House are what messages Francis will deliver and how exactly he will choose to deliver them.

“This pope is a very independent figure,” Charlie Kupchan, senior director for European affairs on the National Security Council, told reporters Thursday, “and we know from his previous travels that we don’t know what he’s going to say until he says it.”