Washington (AFP) - Pope Francis received a rapturous welcome to Washington on Wednesday but did not shy away from controversy, addressing church sex abuse and urging action on immigration and climate change.
President Barack Obama was clearly delighted to welcome to the White House a pontiff who can lend moral and spiritual force to his own priorities, but others may be left uncomfortable by the pope's stances.
Meeting Catholic bishops in Washington, he praised their handling of the child sex abuse scandal that rocked the US church.
"I realize how much the pain of recent years has weighed upon you," he said.
"And I have supported your generous commitment to bring healing to victims... and to work to ensure such crimes will never be repeated."
The Argentine pontiff waded into another bitter US political debate when he urged the church to embrace new immigrants, speaking "not only as the Bishop of Rome, but also as a pastor from" the developing world.
"Perhaps it will not be easy for you to look into their soul. Perhaps you will be challenged by their diversity. But know that they also possess resources meant to be shared," he said.
He later moved on to conduct his first mass in North America, a ceremony to canonize a Franciscan friar who brought Christianity to California, Junipero Serra -- a figure also shrouded in controversy.
Native Americans hold Serra responsible for the suppression of their centuries-old culture and the death of many thousands of their ancestors.
Consternation over his elevation to sainthood did not overshadow the visit, however, and Francis was cheered by euphoric crowds with breathless wall-to-wall televised coverage as he toured Washington's stately boulevards.
- 'Welcoming the stranger' -
Obama, America's first black president, gave the first Latin American pope an effusive welcome to the White House, praising his moral leadership.
"I believe the excitement around your visit must be attributed not only to your role as pope, but to your unique qualities as a person," Obama said, praising Francis' humility, simplicity and generosity of spirit.
Though Francis has inveighed against the materialism that the United States seems to embody like no other country, he is also a potential political ally for Obama, sharing many of his progressive goals and bringing along many of America's 70 million Catholics.
Speaking in fluent, if accented, English, the 78-year-old returned the warm blessings of his host.
"As the son of an immigrant family, I am happy to be a guest in this country, which was largely built by such families," he said.
Francis said he would address Congress "to offer words of encouragement to those called to guide the nation's political future in fidelity to its founding principles."
That may come as good news to a five-year-old American-born girl whose parents are from Mexico, who caught the attention of Francis -- and of the world.
As Francis drew nearer and nearer in his open-sided popemobile and the crowd in Washington whooped and squealed, little Sofia Cruz clambered over a metal barrier, darted out onto stately Constitution Avenue and headed straight for the pontiff -- Secret Service agents be damned.
"She handed the pope a letter asking him to support the drive to legalize undocumented migrants living in the United States," her family's parish in Los Angeles said, contacted by AFP. More than 11 million people without legal residency, like her parents, could be deported unless immigration reform is passed.
Obama lauded Francis for reminding the world that "the Lord's most powerful message is mercy."
"That means welcoming the stranger with empathy and a truly open heart, from the refugee who flees war-torn lands to the immigrant who leaves home in search of a better life," Obama said.
Their message may also resonate strongly in a Europe convulsed by a refugee crisis.
And, as many US conservatives question the very existence of man-made climate change, Francis and Obama made a de facto joint appeal for action.
"Holy Father, you remind us that we have a sacred obligation to protect our planet, God's magnificent gift to us," Obama said.
Francis took up the call.
"Accepting the urgency, it seems clear to me also that climate change is a problem which can no longer be left to a future generation," Francis said.
- Pomp and circumstance -
The pope was afforded a full ceremonial welcome and a 40 minute one-on-one meeting with Obama in the Oval Office.
But the White House held off a planned 21-gun salute that would not have chimed with the pope's stature as a man of peace.
That was the only expense spared during a historic first visit to Washington -- a political city that shrugs when presidents, queens and sheikhs roll through.
The visit was a political mirror of pope Benedict's 2008 visit to George W. Bush's White House. Those two leaders were as conservative as their successors are progressive.
Still, the White House insisted it is not co-opting a holy man in order to batter Republican foes in Congress.
"The goal of the pope's visit, and certainly the goal of the meeting was not to advance anyone's political agenda," said White House spokesman Josh Earnest.
The Vatican played a crucial role in brokering talks between Cold War foes Havana and Washington that led to the recent restoration of diplomatic ties.
But the pope told reporters that he would not specifically bring up Washington's embargo of Cuba in his speech Thursday before American lawmakers, who largely favor a tough line with Havana.
Republicans are already crying foul.
Congressman Paul Gosar, who is Catholic, declared he would boycott the pontiff's address to protest his "leftist" views.
- 'The people's pope' -
Nevertheless, there is no mistaking the political value of enlisting a popular pope's moral authority.
Seven out of ten Americans have a favorable impression of Francis, according to a Washington Post-ABC poll.
The pontiff will make two speeches during his visit, the address to Congress and another to the United Nations on Friday.
He will wrap up his historic six-day US trip on Saturday and Sunday in Philadelphia at an international festival of Catholic families.