Tensions ran high on Thursday among lawmakers, with the House and Senate Democratic leaders calling on Mr. Ryan to remove Mr. Nunes from his chairmanship and one senior Republican senator cautioning that his House colleagues should slow down their push to release the document.

Republicans and Democrats on the Intelligence Committee spent the day arguing over charges by Democrats that the Republicans had made “material changes” to the memo after the committee voted to release it but before it was transmitted to the White House for review. Representative Adam B. Schiff of California, the top Democrat on the Intelligence Committee, wrote in a letter late Wednesday that the committee needed to restart the process and vote on the revised memo.

Republicans quickly countered that Mr. Schiff was “complaining about minor edits” and said their vote was “absolutely procedurally sound.” But a senior Democratic official familiar with the changes said the Democrats had found five material differences in the versions of the memo, including one that the official described as an apparent effort to water down the Republican findings. There were six separate changes to grammar or word choice, the official said. It was not immediately clear whether the changes were related to those requested by the F.B.I.

In a sharply worded letter of her own, Representative Nancy Pelosi of California, the House Democratic leader, called on Mr. Nunes to be removed as the Intelligence Committee’s chairman.

“Congressman Nunes’s deliberately dishonest actions make him unfit to serve as chairman, and he must be removed immediately from this position,” she wrote, adding, “The integrity of the House is at stake.”

Mr. Ryan dismissed the idea during his afternoon news conference, saying that the Democrats were merely “playing politics.”

Mr. Ryan — speaking in part to his Republican colleagues — urged readers of the memo not to “draw lines” between the material discussed in it and the work or character of Mr. Mueller or Mr. Rosenstein.