WASHINGTON (AP) — In a landmark event that could have many holding their breath, Pope Francis has agreed to address a joint meeting of Congress this fall. That sets the stage for an oration by an outspoken pontiff whose views on immigration and global warming clash with those of many Republicans who run the House and Senate.

Francis will speak Sept. 24, marking the first time the head of the world's Roman Catholics will address Congress. It will come during the first U.S. visit of Francis' two-year-old papacy, a trip also expected to include a White House meeting with President Barack Obama, a speech to the United Nations in New York and a Catholic rally for families in Philadelphia.

Saying he had "a bit of good news," House Speaker John Boehner delivered first word of Francis' speech at his weekly news conference Thursday.

"We're humbled that the Holy Father has accepted our invitation and certainly look forward to receiving his message on behalf of the American people," Boehner, R-Ohio, told reporters.

House Minority Leader Nancy Pelosi, D-Calif., said in a written statement that she looks forward to "hearing his call to live our values, to protect the poor and the needy, and to promote peace."

When he speaks to lawmakers, Francis will address a Congress that is 31 percent Catholic, well above the 22 percent of all Americans, according to a survey released last month by the nonpartisan Pew Research Center. Boehner and Pelosi are both Catholic.

Francis, an Argentinian Jesuit and the first pope from the Western Hemisphere, has made helping immigrants a cornerstone of his papacy and has called on wealthy nations to do more for the poor.

By this summer, he also plans to release an encyclical, or teaching document, on climate change, which he says is mostly manmade. He plans to use his trip to the U.S. to urge world leaders to take bold steps to curb global warming ahead of this fall's U.N. climate change conference in Paris.

Republicans have battled Obama's efforts to make it easier for many immigrants in the U.S. illegally to remain in the country, and want to strengthen border security to keep more of them out. Many of them have also opposed efforts to reduce pollutants that contribute to global warming.

Francis, 78, has shown a willingness to publicly call on political leaders to follow some of his values. In a pair of speeches to European leaders last November, he urged them to create jobs and help immigrants gain acceptance.

"We cannot allow the Mediterranean to become a vast cemetery," he said, referring to the thousands of immigrants annually who try reaching Europe across that sea.

"He has a track record of challenging people," said Mathew Schmalz, a religious studies professor at the College of the Holy Cross in Worcester, Massachusetts. "I don't think he'll be overawed by Congress."

Democrats may not be immune to Francis' views, either.

He has condemned abortion and the use of artificial contraception, and called marriage between a man and a woman a "fundamental pillar" of society. However, he has not emphasized these issues as much as immigration and poverty.

Boehner's announcement follows his controversial invitation to Israeli Prime Minister Benjamin Netanyahu, who will address Congress about Iran on March 3, two weeks before he seeks re-election. Boehner made that offer without consulting Obama, angering the White House and congressional Democrats.

At the National Prayer Breakfast on Thursday, Obama said he was eager to welcome the pope to the U.S.

"Like so many people around the world, I've been touched by his call to relieve suffering, and to show justice and mercy and compassion to the most vulnerable," the president said.

Francis' predecessor, Pope Benedict XVI, visited Washington and New York during a 2008 trip. That visit included a meeting with President George W. Bush at the White House, a celebration of Mass at Nationals Park and a speech at Catholic University.

Paul VI became the first pope to visit the United States with a 1965 trip that included an appeal for peace at the United Nations at the height of the Vietnam War. He did not travel to Washington during the visit.

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