Pope Francis travels Tuesday from Cuba to the United States, trading the warm welcome he received on the communist island for a slightly chillier reception — at least in some quarters — from its old Cold War foe.

The pope, who played a key role in brokering the two countries’ recent rapprochement, will conclude his trip to Cuba with a mass and a blessing in second city Santiago, then depart for his first-ever visit to the United States. President Barack Obama and First Lady Michelle are to greet him at Andrews Air Force Base outside Washington at the start of an itinerary that includes landmark speeches to Congress and the UN General Assembly.

Francis, 78, has had a packed schedule since arriving Saturday afternoon in Cuba — three cities, two masses, various blessings and prayer services, countless handshakes with adoring crowds, and meetings with both Fidel and Raul Castro, the brothers who have ruled the Caribbean island since its 1959 revolution.

He has at times looked tired in the tropical heat, but that has done little to dampen the enthusiasm of the fans and faithful who have flocked to see the first Latin American pontiff, who is immensely popular here for his part in fostering the US-Cuban thaw.

The Argentine pope is broadly popular in the United States, as well — 66 percent of Americans approve of him, according to one recent poll, compared to 80 percent of Cubans, in a separate poll.

But for some observers, the dominant themes of Francis’s papacy — concern for the poor, his strong stance in favor of action on global warming and his critique of consumerism — can be read as an indictment of the American way of life.

That was underlined ahead of his trip when Republican Congressman Paul Gosar, who is Catholic, declared he would boycott the pontiff’s historic address to Congress to protest his “leftist” views.

The pope will not have won over such conservative critics with his Cuba visit, during which he has politely refrained from chastising the communist regime for its crack-downs on dissidents and curbs on civil liberties.

In fact, he had what a Vatican spokesman described as a “very informal and friendly” conversation with 89-year-old Fidel, the leader who defied 10 US presidents across half a century of enmity. In 2006 Fidel handed power over to his brother Raul, now 84.

Francis is expected to be more provocative in the United States as he addresses Congress Thursday and the United Nations Friday. The Jesuit pope carefully prepared his speeches for Washington and New York all summer long.

His topics will include critiques of the dominance of finance and technology; a condemnation of world powers over the conflicts gripping the planet; appeals to protect and welcome immigrants; and climate change, including a bold appeal for a radical revolution of the energy industry and a slowdown in growth. His visit will take place under tight security, with US authorities nervous over the complexities of protecting a pope who insists on traveling in an open vehicle to be close to the masses.

The visit poses a particular security headache in New York, where Francis plans to criss-cross Manhattan at a time when 170 world leaders will be in town for the UN General Assembly. He will preside over an inter-faith ceremony at Ground Zero in the south, visit a Harlem Catholic school in the north and greet the crowds on a procession through Central Park.

In Philadelphia, his final stop, he will attend an international festival of Catholic families Saturday and Sunday, delivering his final mass of the trip.The 10,000 tickets for the mass were gone within 30 seconds of going online.Tickets were also snapped up with dizzying speed for events in New York and Washington.