With today’s arrival of Pope Francis in the United States, there is simmering controversy over the Obama administration’s guest list for his visit to the White House, especially among conservative commentators who believe that the president should not have invited people at odds with the Vatican’s positions on gay clergy, same-sex marriage and abortion.

On Monday, Republican presidential hopeful Mike Huckabee waded into the debate with a tweet that said: “Classless decision by @POTUS to transform @Pontifex visit into a politicized cattle call is an insult to millions of Catholics.”

But the Vatican and White House played down reports of differences over the guest list, which includes the first openly gay Episcopal bishop, a leader for transgender rights, a gay Catholic blogger and a prominent nun-lobbyist  who bucked the bishops on the Affordable Care Act — for an event on the South Lawn to be attended by about 15,000 people.

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A Vatican source involved in the planning of the pope’s trip said it made sense not to “put him in an embarrassing situation.” It wasn’t a big worry, the source added, if there were a small handful of open church dissenters among the thousands.

Moreover, the pope has met with Catholics from the gay and lesbian community and has said he would refrain from judging them.

White House spokesman Josh Earnest said on Monday,  “there’s plenty of opportunity for others to inject politics into this situation.  It certainly is a protected constitutional right of theirs to do that.  But that's not what the president is interested in.”

Neither the White House nor the Vatican denied that there had been discussions about the guest list. An American source close to the planning said it seemed there was a “misunderstanding” that has been cleared up and that the crowd at the White House would be diverse in views.

Asked if anyone from the Vatican had raised the issue either with the White House or with the  U.S. delegation, the Vatican spokesman, the Rev. Federico Lombardi, who is traveling with the pope, e-mailed this statement to The Post: “I can only say that the invitations are in the responsibility of the White House. There has been no official statement from the Vatican on this issue.”

The debate over the invitations has been fueled by online conservative critics. An article by Thomas Williams in Breitbart last week said, “In a stunning show of political indecorum, Obama has invited a series of individuals who publicly flout Catholic teaching.”

Ed Morrissey on a site called Hot Air said, “I’m curious. When the Saudis visited the White House this month, did Obama invite women’s-rights activists to dinner with them?”

And a Wall Street Journal article on Sept. 17 quoted a single unnamed Vatican source saying the Holy See was worried that any photos of the pope with guests at the White House welcoming ceremony on Wednesday could be interpreted as an endorsement of their activities.

But on Fox News on Sunday, the Rev. Thomas Rosica, who works in the Vatican’s press office, said, "If some Vatican officials unnamed have expressed concern, that's their issue and they should come forward and give their name.” He added,  "There are 15,000 or so people invited to the White House and there are many pro-life people in that audience."

On Monday, Earnest referred reporters to Rosica’s comments and said “there is no plan or strategy that's been put in place to try to stage an event that will advance anybody’s political agenda.”

Meanwhile, people who have received invitations were excited at the prospect of seeing or meeting the pope and president. “I’m still in such shock over everything,” said Aaron Ledesma, who writes a blog called The Gay Catholic and who wrote to the White House office of correspondence and received an invitation.

Ledesma, 23, who came out two and a half years ago, said that the pope’s comments saying he would not judge gay and lesbian members of the church were important to him. “I struggled for a long time not just with my faith but also with being a gay man. If I had heard messages like this when I was 13, it would have changed everything,” he said.

Regarding those who have said that the president shouldn’t have invited people like him, Ledesma said, “what Pope Francis is going to see is America and that’s a nation of diversity.”

He added, “I was bullied as a kid. Nobody’s going to bully me out of my faith today.”