Pope has approval rating any US politician would pray for

During the visit of Pope Francis to the US, which starts on Tuesday, the pontiff will address a group of 200 poor and sick beneficiaries of Catholic charities in Washington, visit a school for people on a low income and immigrants in New York and meet inmates at a Philadelphia prison.

Taken together with his stop in Cuba, this is the longest trip by the Francis papacy – and certainly one of the most important. The US engagements are a continuation of the pope's outreach to the less well-off in society, only this week it takes place in one of the richest countries in the world.

"That is quite a powerful symbol – that he would spend time with people who are indigent and not want to capitalise every waking minute meeting powerful constituencies," said Bruce Morrill, professor of Catholic studies at Vanderbilt University and, like Francis, a Jesuit.

Former archbishop of Buenos Aires Jorge Mario Bergoglio has, as pope, scored approval ratings among the American public that any politician would pray for.

His energetic and outspoken defence of the vulnerable and his scorching critiques of the excesses of capitalism and the treatment of immigrants and the environment have won broad appeal, and will likely rattle the cages of some powerful constituencies, particularly during the US presidential race.

Francis will, unlike any of three previous popes who visited the US, have unprecedented platforms to preach his message of humility and inclusion. Visiting the US for the first time, he will meet President Barack Obama in the Oval Office on Wednesday and the following day be the first pope to address a joint meeting of the US Congress. On Friday he will speak at the United Nations in New York.

His left-leaning messages put him at odds with some of the bedrocks of American society. The man who carries his own suitcase and made his home a room in the Vatican guesthouse instead of the Apostolic Palace when he became pope has attacked consumerism and materialism. He has denounced the unbridled pursuit of money "the dung of the devil" and a "structurally perverse" global economic system where, at its core, sits the US.

Jeb Bush challenge

Should he use the same rhetoric in some of the 18 speeches he delivers on his visit to Washington, Philadelphia and New York this week, he will likely rile American political conservatives again.

His critics in the US have tried to pigeonhole Francis in ideological boxes. Conservative talk-show host Rush Limbaugh has branded him a Marxist; others have described him as a communist or socialist.

Francis has said he’s not preaching communism, but the Gospel, by challenging systems that “idolise” money over people and criticising the failures of trickle-down economics so cherished by US Republicans.

"When he speaks to Congress, people will have their charts out to see what he is saying against Republicans and Democrats but that will miss what he is doing," said Vincent Miller, professor of Catholic theology and culture at the University of Dayton in Ohio.

“He is going to be offering this challenge of mercy: where do you open your hearts and eyes to what is going on in the world and how do you do something about it? That’s hard for politicians to wriggle out of.”

The pope’s ideology is tricky to map. Some liberals have warmed to the greater inclusiveness he has brought to the church but feel he should have gone further and reformed thinking on same-sex marriage and other issues that have driven people from the church.

While his socially conservative positions appeal to the right in the US, some on that end of the political dial feel he has gone too far – for example, in his encyclical Laudato Si (Praise Be) in June when he argued that global warming was largely man made, caused by over-consumption.

Republican presidential candidate Rick Santorum has said Francis should "leave science to the scientists", while Jeb Bush has also challenged the pope on the issue. "I don't get economic policy from my bishops or my cardinals or my pope," said Bush, a devout Catholic, at the time of the encyclical.

Francis's address to a Republican-controlled Congress comes at a time when Donald Trump tops the polls in the race with nativist, anti-immigrant rhetoric that has won over many grassroots Republicans who will pick their party's nominee.

Embracing immigrants

“Trump’s anti-immigrant discourse has found a fair amount of traction and that has been at the top of Pope Francis’s agenda so we can expect him to talk about how the US has historically been a country of immigrants, has welcomed refugees from around the world and that the country should continue to do so, particularly in the context of the Syrian refugee crisis in Europe,” said

Andrew Chesnut

, professor of religious studies at Virginia Commonwealth University.

On Wednesday, Francis will canonise the 18th century Franciscan Junípero Serra, who founded nine missions in present-day California, at a Mass celebrated in Spanish. Many see this as an opportunity for Francis to make a big statement about embracing immigrants.

"This gesture recognises, in spite of what some xenophobic candidates might indicate, how Hispanics have been part of the United States since the very beginning," said Archbishop Thomas Wenski of Miami.

The popularity of Trump’s bombast about building a wall along the Mexican border to keep criminals out, deporting all illegal immigrants and ending birthright citizenship means that anything the pope says on the issue will stir the domestic political debate.

"By talking to the joint session of Congress the pope is noting that these issues are not limited to one particular religious group over another. It is not a Catholic issue, especially his critiques of the underbelly of capitalism and the document on climate change – everybody has to be involved," said Christopher Born, associate professor of religion and culture at Catholic University of America.

When Francis speaks on Capitol Hill, it will be one of just three speeches in English he makes on on his five-day visit to the US. The other two are his address at the White House and his prayer at the memorial to the victims of the September 11th, 2001 attacks in New York.

He will speak mostly in Spanish, his native tongue, but crucially to a growing audience for the church and an increasingly important force in American politics: the Latino community.

Catholics account for just one in five Americans but the US is home to the fourth-largest Catholic population, or more than 68 million people – the country’s single biggest faith group. Latinos make up 38 per cent of that group and are an increasing proportion of the Catholic parishioners as a result of immigration and high birth rates.

More significantly, about 60 per cent of young Catholics are Spanish speaking, so they represent the future.

Shortage of priests

Francis certainly needs them for the church’s future. A poll by Pew Research found that one in 10 Americans said they were raised Catholic but were no longer with the faith. Mass attendance has dropped from 41 per cent to 24 per cent of adult Catholics over the past 38 years and there is a growing shortage of priests, with about 3,500 of more than 17,000 parishes without a resident priest.

In addition, the church is struggling in the wake of clerical sex-abuse scandals. Three dioceses have filed for bankruptcy to limit payouts to victims and to ringfence church assets. These issues make the pope’s appeal among young Latino-American Catholics all the more pressing.

Francis’s fans, regardless of which language he speaks, will hope he will not be scripted during his visit to the point of curbing its important messages.

"I just hope his American handlers are not going to hedge him in too much," said Irish priest Fr Michael Collins, author of Pope Francis: A Photographic Portrait of the People's Pope, who is in the US for the visit.

“When he is in Latin America, he usually says that they wrote a good speech and then he goes off with off-the-cuff comments. I think he is going to be a vitamin shot for the church in America.”