Years before the migrant crisis that reshaped American politics in recent years, Pope Francis made immigration a defining theme of his papacy, including during a 2015 visit to the U.S.

“As the son of an immigrant family, I’m happy to be a guest in this country, which was largely built by such families," he told the audience during a speech on the South Lawn of the White House.

On that same visit, he became the first pope to address Congress, telling lawmakers that migrants should be viewed as persons, and that people's response should be to listen to their stories — “to respond in a way which is always humane, just and fraternal.”

Francis took that message all over the world, advocating on behalf of those displaced by violence, persecution and poverty.

Migration was the focus of a 2016 trip to Ciudad Juarez in Mexico, near the U.S. border. Afterward, Francis sparked a firestorm with comments about then-presidential candidate Donald Trump.

"A person who thinks only about building walls, wherever they may be located, and not building bridges, is not a Christian," he said.

“I am a Christian. And I’m proud of it,” Trump shot back. “For a religious leader to question a person’s faith is disgraceful.”

Trump, who had previously criticized the pope for his trip to Mexico, calling him “a political person,” retweeted photos of the Vatican City walls, suggesting the pope was guilty of hypocrisy.

Fast forward to Trump’s second term, and another series of clashes, Francis criticized mass deportations in forceful terms and repudiated JD Vance after the vice president cited Catholic doctrine in justifying immigration policy.

Vance visited the pope on Sunday, hours before his death.

David Gibson of Fordham University, a close observer of the Vatican, said despite his concerns with U.S. immigration policy, Francis understood the need for limits.

Francis was not for “open borders, at all,” Gibson said. “He’s very clear about that. We have to have to regulate immigration, but we need to welcome the stranger.”

Francis also in recent months spoke out against Israeli military actions in Gaza, calling for an investigation to determine if they constituted genocide.