ROME — A diplomatic rift over how to deal with the Chinese government widened Wednesday as Secretary of State Mike Pompeo urged the Catholic Church to deploy its moral authority on behalf of persecuted believers in China.

The dispute is about an arcane negotiation over appointing Catholic bishops in China, a country the Pompeo has described as the world’s worst abuser of human rights and condemns nearly every week. But it is rooted in Pompeo’s belief that religious liberty is the foremost freedom necessary for all other freedoms to flourish.

“Nowhere is religious freedom under assault more than in China,” Pompeo said in a keynote speech Wednesday before a symposium called “Advancing and Defending International Religious Freedom Through Diplomacy.” The event was sponsored by the U.S. Embassy to the Holy See and held in an ornate ballroom at a luxury hotel on the storied Via Veneto, a short block from the U.S. mission.

Pompeo said the Chinese Communist Party is trying to “snuff out the lamp of freedom, especially religious freedom, on a horrifying scale.” He quoted two conservative popes, John Paul II and Benedict XVI, before mentioning the more liberal Pope Francis, and urged the church to deploy its moral authority “in glorious, glorious service of human dignity.”

Two senior Vatican officials in attendance, in remarks to Italian reporters in the hallways, bristled at Pompeo’s efforts to push the Vatican into a more hard-line stance with Beijing in negotiations to extend an agreement on nominating bishops.

A provisional deal with China, which is set to expire Oct. 22, is the most controversial — and potentially important — diplomatic venture of Pope Francis. The deal was an attempt to thaw relations between Beijing and the Holy See and end the system in which bishops were appointed by Chinese state authorities, sometimes without papal approval.

Because of that, the church in China had effectively split in two — with some bishops operating officially under the state and others underground, loyal to the pope. The terms of the deal were never made public, but Francis said in 2018 that he would have final say in the naming of new bishops.

In recent weeks, Pompeo has repeatedly criticized the potential rapprochement between the Vatican and Beijing. In a Sept. 18 essay in the conservative magazine First Things, he decried Beijing’s persecution of Muslims, Catholics and Protestants and declared, “Now more than ever, the Chinese people need the Vatican’s moral witness and authority in support of China’s religious believers.” Later, he wrote in a tweet that the Vatican “endangers its moral authority, should it renew the deal.”

When asked what the Holy See thought of Pompeo’s opinion piece, Archbishop Paul Gallagher, the Vatican’s secretary for relations with states, replied: “It was received critically.”

“Normally when you are preparing these visits between high-level officials, you negotiate the agenda of what you are going to talk about privately, confidentially. It’s one of the rules of diplomacy,” he told reporters on the symposium’s sidelines.

Cardinal Pietro Parolin, the Vatican’s top diplomat who is scheduled to meet with Pompeo on Thursday, told reporters that Pope Francis would not meet with Pompeo under a policy to avoid exchanges with politicians during an election season, out of concerns it could imply a papal endorsement. He said the Vatican would continue to pursue its policy of engagement with the Communist rulers in Beijing.

As criticism of his words flowed into the public realm, Pompeo defended what he said as an effort to bolster human rights.

“I wrote that piece to honor the moral authority of the Catholic Church and its capacity to influence and make things better for people all across the world,” Pompeo said at a news conference with Italian Foreign Minister Luigi Di Maio. “They have historically stood with oppressed peoples all around the world. The piece was written and our policy has been all along to bring every actor who can benefit the people of China from — to take away the horrors of the authoritarian regime the Chinese Communist Party is inflicting on these people. That was our mission set, and it will remain our mission set. It’s been so long before the election; it will remain so after the election.”

The flap between the White House and the Vatican has gotten plenty of attention in Italy, a heavily Catholic country. One mainstream outlet, the Corriere della Sera, on Wednesday ran a headline describing a “frontal collision” between the city-state and the United States, and said Trump was trying to “exploit” the pope.

Marco Politi, a papal biographer, said Pompeo had committed an “intolerable diplomatic attack” against the Vatican.

“Clearly the Trump administration has now unleashed a cold war against China on every level, economic, political, with Huawei, the ‘China virus,’ ” Politi said, referring to the Chinese technology company and how the administration often refers to the coronavirus. “The pope does not want to be conscripted into this cold war.”

Francesco Sisci, a researcher and writer on China-Vatican affairs at Renmin University in Beijing, said the Vatican’s dealings with China remain highly controversial within the church and Pompeo might have been granted an audience if he had not antagonized the Vatican with his “tone.”

“Pompeo’s article was not carefully calibrated for the Vatican, which resulted in the whole Catholic Church rising up and saying, ‘How does he dare?’ ” said Sisci, who has interviewed Parolin and Francis on their diplomacy with China. “He put himself in the middle of an internal Catholic controversy.”

Sisci said there is a sense among Vatican officials that China has not made as much progress as hoped to mend fences with underground congregations. But the Vatican believed China’s efforts to heal the schism has been interrupted by the covid-19 pandemic and wanted to give Chinese officials more time, Sisci said.

“Of course China’s human rights situation is very complicated, but in all fairness this is moving the goal post when it comes to the Catholic Church,” he said. “If we are talking about the Catholics in China, there have been results. It’s not incredible, but it’s results.”

Harlan reported from Florence, and Shih from Taiwan. Stefano Pitrelli, also in Florence, contributed to this report.