House Chaplain Patrick Conroy's sudden resignation has sparked a furor on Capitol Hill, with sources in both parties saying he was pushed out by Speaker Paul Ryan (R-Wis.).

Conroy's own resignation announcement stated that it was done at Ryan's request.

"As you have requested, I hereby offer my resignation as the 60th Chaplain of the United States House of Representatives," the April 15 letter to Ryan, obtained by The Hill, states.

Through his office, Conroy, who has served as chaplain since 2011, declined to comment on Thursday. His resignation is effective May 24.

Four different sources - two from each party - say Conroy was told that he must retire or that he would be dismissed.

The message from Ryan was delivered by his chief of staff, Jonathan Burks.

The issue has riled House Minority Leader Nancy Pelosi (D-Calif.), who broached the episode during the Democrats' whip meeting in the Capitol Thursday morning.

A bipartisan group of lawmakers are planning to send a letter to Ryan requesting additional information regarding Conroy's dismissal; the group is currently circulating the letter among colleagues to collect more signatures.

The thinking among Democrats is that Ryan pushed Conroy out "because Republicans thought he was aligned with Democrats," according to a senior Democratic aide familiar with the discussion.

House chaplains, who offer an opening prayer each day the House is in session, are supposed to be nonpartisan.

It's unclear exactly what if any political dispute, however, led to the chaplain's dismissal.

A Democratic lawmaker said that the Speaker took issue with a prayer on the House floor that could have been perceived as being critical of the GOP tax-cut bill.

On Nov. 6 - the first day of the markup on the GOP's tax bill - Conroy in a prayer urged lawmakers to ensure the legislation did not exacerbate the nation's gaping class disparities.

"May all Members be mindful that the institutions and structures of our great Nation guarantee the opportunities that have allowed some to achieve great success, while others continue to struggle," Conroy said at the time. "May their efforts these days guarantee that there are not winners and losers under new tax laws, but benefits balanced and shared by all Americans."

A senior GOP aide said Conroy's exit "was not because of any particular prayer."

Ryan's and Pelosi's offices agree that Pelosi was told in advance that the chaplain was leaving.

AshLee Strong, a spokeswoman for Ryan, said it was Ryan's decision, but declined to offer a reason for the move. She added that Pelosi and her office "were fully read in and did not object."

"The speaker told Leader Pelosi that he would not move forward with the decision if she objected and she chose not to," Strong said.

In a separate statement to media outlets late Thursday, Strong said, "The speaker consulted with the minority leader, but the decision was his. He remains grateful for Father Conroy's service."

Pelosi's office disputed that the Democrat did not object.

"Leader Pelosi was given advance notice by Speaker Ryan," said a Pelosi spokesman, but she "also made it clear to Speaker Ryan that she disagreed with this decision."

A second Democratic aide said Conroy's ouster was "largely driven by a speech on the tax bill that the Speaker didn't like." But the source also offered a second reason.

"Some of the more conservative evangelical Republicans didn't like that the Father had invited a Muslim person to give the opening prayer," the source said.

When Pelosi, who is Catholic, informed members of her whip team on Thursday morning that Conroy was pushed out against his will, it "shocked" the members, according to one lawmaker.

Catholic members on both sides of the aisle were furious to learn that Conroy's retirement was not voluntary, according to multiple sources, including one Republican lawmaker and one Democratic member.

Ryan, who is also Catholic, has appointed Rep. Doug Collins (R-Ga.), an Air Force Reserve chaplain, as well as Reps. Mark Walker (R-N.C.) and Tim Walberg (R-Mich.), both former pastors, to lead the search effort to find a replacement.

Conroy's arrival on Capitol Hill was also marked with some controversy. The Jesuit priest was nominated by former Speaker John Boehner (R-Ohio) in May 2011, but Pelosi urged additional vetting of the pick after learning that Conroy was then working for a Catholic religious order - the Oregon Province of the Society of Jesus - that had agreed just months earlier to pay $166 million to victims of sexual abuse going back decades.

There was no evidence that Conroy was involved in the scandal, nor did Pelosi suggest that was the case. After further questioning, she endorsed his nomination.

- Juliegrace Brufke and Scott Wong contributed to this report, which was updated at 8:23 p.m.