Cardinal Daniel N. DiNardo, the archbishop of Galveston-Houston in Texas and president of the U.S. Conference of Catholic Bishops, said the allegations by Archbishop Carlo Maria Viganò in a letter released over the weekend deserved responses that are "conclusive and based on evidence."
"Without those answers, innocent men may be tainted by false accusation and the guilty may be left to repeat sins of the past," DiNardo said in a statement.
He also called for a meeting with the pope to "make reporting of abuse and misconduct by bishops easier, and improve procedures for resolving complaints against bishops."
Marco Tosatti, an Italian journalist and veteran Vatican watcher, said that he helped Viganò, a former Vatican ambassador to the U.S., write the letter and that the prelate's reason for publishing the text was to "clean the church" and to "clean his conscience."
The call for action came as the Vatican struggled to contain the fallout from the 11-page letter that alleges that Francis knew about sex abuse allegations against former Cardinal Theodore McCarrick for years, but chose to cover up the charges and promote him before accepting his resignation last month.
Michael Walsh, a historian on the papacy and the editor of the Oxford Dictionary of Popes, said tensions between reformists like Francis and conservatives like Viganò have been bubbling up since Francis was elected pope in 2013.
Francis, he says, was in part elected on an agenda to reform theCuria, which serves as a form of governmental cabinet whose members handle both administrative and judicial functions for the church at large. But the pope's efforts have met resistance from a group of conservative cardinals and bishops who are opposed to policies such as allowing divorced and remarried people receive Holy Communion.
"The war within the Vatican has been going on for a long time," Walsh said. "What's new is the degree of discontent and particularly that people are vocalizing it and articulating it."
In the letter, Viganò said Pope Benedict XVI imposed sanctions on McCarrick in 2009 or 2010, ordering him to withdraw to a lifetime of prayer and penance, but that Francis chose to rehabilitate him, "cover" for him and elevate him to "trusted counselor."
Viganò also identifies by name the cardinals and U.S. archbishops who he claims were informed about the McCarrick affair — a shocking expose for a Holy See official to make. NBC News could not confirm the letter's claims and Viganò offered no evidence to back up his allegations.
The letter came midway through Francis's highly charged weekend visit to Ireland, which was itself dominated by the church's sex abuse scandal. It also came days after Francis begged forgiveness after a grand jury report that found that more than 1,000 children had been sexually abused by "predator priests" in Pennsylvania for decades.
Viganò said the truth. That’s all.
The state's attorney general, Josh Shapiro, who is leading the investigation, told NBC's "Today" show on Tuesday that the grand jury uncovered evidence that the Vatican had knowledge of a "systematic cover-up,"but that he could speak specifically about Pope Francis.
Viganò's accusations, coupled with the Pennsylvania report, have led to a crisis of confidence in the U.S. church, and Walsh said there have even been calls for all American archbishops to resign over the scandal.
Several high-ranking members of the clergy named in Viganò's letter have issued statements denying claims they knew of allegations against McCarrick years ago or helped to cover up his alleged abuse.
The archdiocese of Washington issued a statement on Monday denying that Viganò had provided Archbishop Cardinal Donald Wuerl with any information over the alleged sanctions against McCarrick.
"Cardinal Wuerl has indicated that during his entire tenure as archbishop of Washington no one has come forward to say to him, 'Cardinal McCarrick abused me' or made any other like claim," it said.
Cardinal Joseph W. Tobin, the archbishop of Newark, New Jersey, said Viganò's letter contained "factual errors, innuendo and fearful ideology."
As the divisions are laid bare, several members of the clergy have made their allegiances clear, with some vouching for the credibility of Francis and others backing Viganò.
Cardinal Blase J. Cupich of Chicago rushed to the pope's defense. "My experience with the Pope is that as soon as he knows about something, he acts on it," he told NBC Chicago.
In a separate statement Cupich — who was accused by Viganò of being part of a "wicked pact of abuses" and "cover-up of abuses" — said he considered the remarks to be "astonishing" and denied any wrongdoing.
Walsh said Cupich is considered to be a modernizer in the church and that his appointment to the archdiocese of Chicago was celebrated among liberals.
But Viganò also has his backers, including Jean-François Lantheaume, the former first counselor at the apostolic nunciature in Washington.
In his letter, Viganò claims Lantheaume told him about a "stormy conversation" between Pietro Sambi, Viganò's predecessor as Vatican ambassador, and McCarrick, as Sambi informed McCarrick of the sanctions imposed on him by Benedict.
"Viganò said the truth. That's all," Lantheaume told the Catholic News Agency, declining to comment further.
Meanwhile, both the Vatican and the pontiff have stayed mum.
Francis on Sunday declined to say whether he was told about the allegations against McCarrick in 2013. He told reporters aboard the papal plane as he was leaving Ireland that he had read the statement but that he wouldn't comment on it, adding that the text "speaks for itself."
"I won't say a word about it," he added.