As Biden and Francis meet, the U.S. Catholic Church remains divided.

VATICAN CITY — Joseph R. Biden Jr. is the third American president Francis has met since becoming pope in 2013. Each meeting has marked a distinct phase not only of his papacy, but also of the political upheaval in the United States and in its Roman Catholic church.

President Barack Obama shared Francis’ global magnetism, celebrity wattage and a focus on immigrants, climate change and the poor. President Donald J. Trump, whose Christianity Francis once questioned for his anti-immigrant policies, ushered in a populist era that helped sideline Francis.

Mr. Biden, a devout Catholic, arrived at a moment when the political polarization in America has become woven into its Catholic church. And the president and pope have become common targets of powerful conservative American bishops seeking to undercut them.

Vatican officials and experts said they doubted that the antagonism of American bishops would come up in the private audience between Francis and Mr. Biden, and that they would instead talk about issues like addressing climate change, caring for the poor and ending the pandemic.

Francis is likely to press the president to ramp up coronavirus vaccine distribution to the developing world, and he rarely misses the chance to speak out against arms dealing and the consequences of war.

Yet factions left and right will be studying the meeting for any clue that the pope is providing political cover to the first Catholic American president since John F. Kennedy against the conservative culture warriors in their church.