WASHINGTON — (CNN) Pope Francis has not commented on the crowded field of U.S. presidential candidates. But after similar situation arose in Argentina, he was not amused.

In 2007, when the future pope was archbishop of Buenos Aires, 18 Argentines ran for president.

“So we are either a fantastic nation with 18 geniuses who can lead the country,” he told two journalists, “or we are a nation of fools who can’t agree.”

Francis is no fan of dictatorships, either. He has called on Cuba and other nations to scrap their “corrupt” regimes and give the people a voice in government.

Too many politicians. Too few. The Pope will soon get an up-close and personal look at both political dynamics.

On Saturday, he will land in Cuba, a communist nation controlled by the Castro brothers for nearly six decades. On Tuesday, Francis will fly to the United States, a country holding a fierce and freewheeling presidential campaign, with at least 20 candidates contending for the White House.

In both countries, Francis will attempt to stay above the partisan fray, according to Catholic officials. But they acknowledge the probability that his every word will be parsed and spun for political advantage.

“He’s coming as a pastor of souls and a prophet, not a politician,” said Archbishop Joseph Kurtz, president of the U.S. Conference of Catholic Bishops. At the same time, the Pope will likely encourage Catholics to put their faith into action, Kurtz added.

Politician or not, this Pope holds sharply political opinions on everything from campaign finance reform to climate change.

Francis has also been open about his aims, saying he wants to influence upcoming summits at the United Nations on sustainable development and care for the environment.

In the United States, meanwhile, the Pope’s popularity has slipped, perhaps because of his political activism.

Less than half of American conservatives say they hold a favorable image of Francis, according to a recent Gallup Poll. The pontiff’s fiery denunciations of the “idolatry of money” and his linking of climate change to human activity, could be partly to blame, Gallup said.

In general, it seems, liberals love it when the Pope gets political, while many conservatives would rather he stick to traditional religious subjects.

With the tensions between the Pope’s political and pastoral roles in mind, here are the five toughest challenges he will face on his trip to the United States and Cuba, September 19-27.

1. Cuba libre?

President Raul Castro has granted Cubans more religious freedom in recent months, and even said that Pope Francis has inspired him to consider joining the Catholic Church.

Castro is expected to attend the Pope’s two public Masses in Cuba, and Vatican officials have hinted that Francis may meet privately with Castro’s brother, Fidel.

If so, the pontiff should take care not to appear too chummy with the Castros, conservative Americans say.

“The Castro brothers are mass-murderers,” said Rep. Chris Smith, a Republican from New Jersey. “They have tortured and imprisoned thousands of dissidents.”

Smith said he expects the Castros to attempt to manipulate the Pope’s message, just as they tried to do during previous papal visits to Cuba in 1998 and 2012.

The congressman also said he is concerned that the diplomatic thaw between Cuba and the United States — a détente aided and encouraged by Pope Francis — does not require the release of political dissidents.

On September 11, Cuba announced that it would pardon 3,522 prisoners ahead of the Pope’s arrival, but none had committed crimes against state security, according to the government.

The Pope’s advisers say he is unlikely to make provocative political statements in Cuba. He is going to confirm and encourage the faith of Cuban Catholics, not condemn the Castros.

But after hearing Francis rail against runaway capitalism, some American conservatives are hoping he will now put communism in his rhetorical crosshairs.

Key question: Will the Pope publicly condemn the Castros’ repressive style of communism?

2. The man on the hill

Nobody knows the proper protocol for a pope addressing a joint meeting of Congress. It’s never been done before.

Will Francis shake hands as he walks to the lectern? Should Congress clap for political points? Would anyone dare be caught on camera not applauding the Pope?

“I would prefer that no one gets up and cheers, claps or shows any response during the whole speech until the very end,” Rep. Dan Lipinski, an Illinois Democrat, told National Catholic Reporter. “Whether or not that would hold, I am not sure.”

Beyond the political theater, Vatican officials know the audience for Francis’ congressional address will likely extend far beyond Capitol Hill. Many poor nations will be watching to see if he takes Congress to task.

“When Pope Francis speaks to slums in South America, he’s talking to the footprint,” a church source told CNN. “When he speaks to the United States, he’s talking to the boot.”

Archbishop Jose Gomez of Los Angeles and other Hispanics have encouraged the pontiff to address immigration reform, an issue that resonates personally with the first Pope from Latin America. Initially, Francis had wanted to enter the United States through its border with Mexico to highlight the plight of immigrants.

The Pope is likely to make a similar point about Latinos’ influence on the United States when he canonizes Junipero Serra, a Spanish missionary, in Washington on September 23.

Conservatives, meanwhile, are encouraging the Pope to condemn abortion, noting that his speech to Congress comes just as some members have threatened to shut down the government over federal funding of Planned Parenthood.

Key question: Will the Pope’s speech to Congress be a pep talk or a stern lecture?

3. The bully pulpit

On September 25, Francis will address world leaders at the United Nations General Assembly. The stated subject is peace, but the Pope’s advisers expect him to range widely, given the rare opportunity to speak to so many world leaders at one time.

Guzman Carriquiry Lecour, secretary of the Pontifical Commission for Latin America, said Francis could speak about persecuted Christians in the Middle East, refugees on the run in Europe, climate change, the drug trade, gun-running, poverty, “ideological colonization,” reckless financial speculation and the technology gap between rich and poor nations.

“It can be expected that the Pope will draw attention to the serious responsibility the United States has within the international community,” Carriquiry said, “and to lead the common work of nations toward more humane solutions.”

In his encyclical on the environment, “Laudato Si,” the Pope criticized the failure of international organizations to confront global crises like climate change.

“It is remarkable how weak international responses have been,” Francis said. Meanwhile, “the Earth, our home, is beginning to look more and more like an immense pile of filth.”

Key question: Can the Pope actually push countries to make tough choices on political issues?

4. Torn in the USA

American Catholics are divided on almost every culture war issue, from abortion to same-sex marriage to climate change.

The gap is widest, according to a recent Pew Research Center survey, between conservatives who attend Mass weekly and “cultural Catholics” who rarely darken a church’s door.

Catholics who attend Mass more often are much more likely to call abortion a sin, say children should not be raised by same-sex couples and believe that the church should not allow remarried Catholics to receive Communion.

While not changing church teaching on key doctrinal issues, Pope Francis has tried to make his church appear more merciful, especially to those on the margins of church life.

Earlier this month, he announced that all priests around the world will be authorized to forgive the “sin of abortion” when the church begins a “Year of Mercy” this December.

And on September 8, Francis radically revised the process by which Catholics may annul their marriages, streamlining steps that many in the church considered too cumbersome and costly.

While church progressives praised both moves, conservatives accused Francis of “vandalizing marriage” by scrapping centuries of Catholic teachings and tradition.

Key question: Can the Pope build a bridge between the liberal and conservative factions of his American flock?

5. Lost sheep

When Francis arrives in the United States, he will find nearly half of the population connected in some way to Catholicism, according to the Pew survey.

But just one-fifth currently call themselves Catholics, and 1 in 10 Americans say they have fallen away from the faith.

There are so many former Catholics in the United States, in fact, that if they formed their own church, they’d be the country’s second-largest religion, after only the Catholic Church itself.

To see that exodus in action, look no further than Philadelphia — the final stop on the Pope’s trip to the United States.

At one time, the city teemed with Catholics, with more than 250,000 students in the church’s schools and people identifying their neighborhood by the local Catholic parish.

But in the last decade, two scathing grand jury reports accused Catholic leaders of covering up the crimes of pedophile priests. Declining funds led to the closure of dozens of Catholic schools and the merging of many parishes. Archbishop Charles Chaput said that when he was appointed to Philadelphia in 2011, the archdiocese was $17 million in debt.

The situation was so bad, Chaput said recently, that he was reluctant to host the World Meeting of Families, the huge Catholic conference that’s expected to draw 700,000 people — including the Pope — to Philadelphia next weekend.

Now, Chaput said, he’s hoping Francis can perform a Philadelphia miracle.

“We’re going to make the church younger and fresher and more enthusiastic,” the archbishop told CNN. “If that happens, it’s going to be worth all the work and all the money that’s gone into preparing for this visit.”

Key question: Can Pope Francis bring lapsed Catholics back into the fold?

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