From his private meeting with President Obama to giving the first-ever papal address before a joint session of Congress, Pope Francis did not shy away from politics during his three-day stop in Washington, D.C. (Julie Percha/The Washington Post)

With the first words that Pope Francis uttered publicly on American soil, he made it clear Wednesday that he does not intend to sidestep the deeply divisive issues that are roiling this country — and indeed, that he plans to fully employ his voice and influence as the spiritual leader of nearly 80 million Roman Catholics in the United States.

Amid the pageantry of a welcoming ceremony on the White House lawn, the first pope from the Americas introduced himself as “the son of an immigrant family. I am happy to be a guest in this country, which was largely built by such families.”

Coming from a Hispanic pontiff, those words were an unmistakable reference to an issue that has come to dominate much of the race for the 2016 Republican nomination, in which front-runner Donald Trump has vowed to deport the estimated 11 million immigrants who are in this country illegally and revoke the constitutional guarantee of citizenship to anyone born here.

The national spotlight will be fixed firmly on the pope for the next week, as throngs of Americans come out to participate in his tour of the United States, which will include an address Thursday to a joint meeting of Congress. He was invited there by House Speaker John Boehner (R-Ohio), who is Catholic. In the audience will be at least three of the 15 Republican contenders for president.

In his brief address at the White House, delivered in English, the pope also congratulated President Obama for "proposing an initiative for reducing air pollution. 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."

Obama's views and those of the pope on the issue of climate change fall squarely on the liberal side of the political divide.

At the same time, some of the pope's words on other subjects reinforced arguments that are being made by conservatives.

He noted the efforts of American Catholics toward "building a society which is truly tolerant and inclusive, to safeguarding the rights of individuals and communities, and to rejecting every form of discrimination."

Francis added: "They are likewise concerned that efforts to build a just and wisely ordered society respect their deepest concerns and their right to religious liberty. That freedom remains one of America's most precious possessions."

The pope specifically noted that a priority of the U.S. bishops has been "to be vigilant, precisely as good citizens, to preserve and defend that freedom from everything that would threaten or compromise it."

For many American conservatives, the threat has become more urgent with the recent U.S. Supreme Court decision legalizing same-sex marriage, which is anathema to the teaching of the Catholic church and some other religions. Since the Supreme Court decision, there has been concern that faith-based groups that hold fast to traditional teachings could lose their tax-exempt status, though many church lawyers think they are protected.

Francis noted that he will be attending the World Meeting of Families in Philadelphia, "to celebrate and support the institutions of marriage and the family at this, a critical moment in the history of our civilization." Francis has in the past called the rise of gay equality a “new sin against God.”

Michelle Boorstein contributed to this report.