Pope Francis is more than head of the Catholic Church — he’s also the head of state of the Vatican, which as a government has possibly the most restrictive immigration and citizenship policies of any nation in the world.

The pope, traveling to the U.S. for the first time, has made a special appeal to Americans to welcome immigrants, using his address to a joint meeting of Congress Thursday to invoke the Golden Rule in demanding generosity toward the millions of Central and South Americans seeking to come to the country.

“Thousands of persons are led to travel north in search of a better life for themselves and for their loved ones, in search of greater opportunities. Is this not what we want for our own children?” he said. “We need to avoid a common temptation nowadays: to discard whatever proves troublesome. Let us remember the Golden Rule: ‘Do unto others as you would have them do unto you.’”

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Immigrant rights groups had eagerly anticipated the pope’s message, as had illegal immigrants themselves.

Sophie Cruz, a five-year-old U.S. citizen whose parents are illegal immigrants from Mexico, broke through the tight security around the pope during a parade on the National Mall on Wednesday to hand him a letter begging him to pressure Congress and the White House to take steps to grant her parents legal status.

The pontiff didn’t mention illegal immigration during his speech Thursday, but did refer to the large numbers of people coming from Latin America. Advocacy groups cheered his words, saying his call for unity and acceptance should temper some of the harsh rhetoric that’s flared recently.

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“At this moment, with many political candidates and elected officials fanning the flames of intolerance and divisiveness, let us hope that our leaders take the Holy Father’s powerful message to heart,” said Frank Sharry, executive director of America’s Voice.

But lawmakers doubted his words would break the legislative stalemate in Congress.

Sen. Ted Cruz, Texas Republican, said he took the pope’s call for compassion to be a celebration of legal immigration — and said he welcomed that.

Rep. Michael Burgess, Texas Republican, said the U.S. is already doing its part to heed calls for compassion.

“The thing that always strikes me when we get into these discussions is the United States takes in more people every year legally than the rest of the world combined,” he said. “You start from that premise — it was 1.7 million last year, you want to add another 400,000 to 600,000 that came in without the benefit of doing it the right way. What is the right number? If over 2 million is not enough, would someone please tell me what that right number is, and would other countries act accordingly.”

The Vatican, for its part, welcomes millions of visitors a year — but allows only a very select few, who meet strict criteria, to be admitted as residents or citizens.

Only about 450 of its 800 or so residents actually hold citizenship, according to a 2012 study by the Library of Congress. That study said citizens are either church cardinals who reside in the Vatican, the Holy See’s diplomats around the world, and those who have to reside in the city because of their jobs, such as the Swiss Guard.

Spouses and children who live in the city because of their relationship with citizens — including the Swiss Guard and workers such as the gardener — have also been granted citizenship. But that means few of the Vatican’s citizens are women.

A Vatican spokesman did not return an email seeking comment on its policy.

The strict policy has left the Vatican open to criticism in the past, including from right-wing political leaders in Italy who want tighter immigration controls in their country and have rebuffed the papacy’s calls for leniency by asking how many refugees live in the enclave.

Pope Francis, however, has taken some steps to mitigate those attacks, matching his call earlier this month for churches to host Syrian refugees with a vow that the Vatican itself would take in a couple of refugee families.

Last week the Vatican government announced it had accepted a mother, father and two children who are Melkite Greek Catholics, and who have asked for asylum in Italy.