President Donald Trump told Russian diplomats last week his firing of "nut job" James Comey had eased the pressure on him, even as the FBI's Trump-Russia investigation had moved into the White House, according to reports Friday that pursued the president as he began his maiden foreign trip.

White House hopes that Trump could leave scandalous allegations at home were crushed in a one-two punch of revelations that landed shortly after his departure. A Washington Post report, citing anonymous sources familiar with the matter, said a senior Trump adviser is now considered a "person of interest" in the law enforcement investigation into whether Trump's campaign associates coordinated with Russia in an effort to sway the 2016 election.

And The New York Times reported that the president had told Russian officials he felt the dismissal of his FBI director had relieved "great pressure" on him. The White House has said the firing was unrelated to the FBI's Russia investigation.

Late Friday, the Senate intelligence committee announced that Comey had agreed to testify at an open hearing at an undetermined date after Memorial Day.

Comey will certainly be asked about encounters that precipitated his firing, including a January dinner in which, Comey has told associates, Trump asked for his loyalty. In the Oval Office weeks later, Comey told associates, the president asked him to shut down an investigation into former national security adviser Michael Flynn.

Comey is known to produce memos documenting especially sensitive or unsettling encounters, such as after the February meeting.

Comey turned down an invitation to testify before the Senate Judiciary Committee.

The new headlines were a fresh indication that Trump would not be able to change the subject from what appears to be an intensifying investigation reaching toward the president and his inner circle.

The White House repeated its assertion that a "thorough investigation will confirm that there was no collusion between the campaign and any foreign entity."

It did not deny the Times report that Trump was critical of Comey to the Russians the day after he fired him.

The Times reported Trump noted the Russia investigation as he told Russian Foreign Minister Sergey Lavrov and Ambassador to the U.S. Sergey Kislyak of his decision to fire Comey.

"I just fired the head of the FBI. He was crazy, a real nut job," the Times reported that Trump said during the May 10 meeting. "I faced great pressure because of Russia. That's taken off."

White House spokesman Sean Spicer called the president's rhetoric part of his deal-making.

"By grandstanding and politicizing the investigation into Russia's actions, James Comey created unnecessary pressure on our ability to engage and negotiate with Russia," Spicer said. "The investigation would have always continued, and obviously the termination of Comey would not have ended it. Once again, the real story is that our national security has been undermined by the leaking of private and highly classified conversations."

As for the separate report of a "person of interest" under investigation, the Post said the senior White House adviser "under scrutiny" is someone close to the president but did not name the person.

Among Trump's senior White House advisers are several former campaign officials, including his son-in-law Jared Kushner, Steve Bannon, Stephen Miller and Kellyanne Conway. In March, Kushner volunteered to answer lawmakers' questions about meetings he had with Russian officials during the transition.

A spokeswoman for House Speaker Paul Ryan said he would not discuss information provided in classified briefings and said the House Oversight committee had already asked for documents related to Comey's firing.

Earlier this week, the Justice Department appointed former FBI Director Robert Mueller to take over the federal investigation in an effort to re-establish independence from the White House.

Deputy Attorney General Rod Rosenstein told Congress Friday he stands by a memo he wrote bluntly criticizing Comey. But he made clear it was not his intention for Trump or other White House officials to use the document to justify firing Comey, which is what they have done.

In closed-door meetings with lawmakers on Thursday and Friday, Rosenstein said he wrote the memo after Trump told him one day before the May 9 firing that he wanted to dismiss Comey. Rosenstein said that though he was personally fond of Comey, "I thought it was appropriate to seek a new leader."

The Justice Department on Friday released the text of Rosenstein's opening remarks for the briefings on Capitol Hill.

Trump has said he plans to nominate a new FBI director soon, but there was no announcement Friday.

The appointment of Mueller as special counsel has drawn generally favorable comments from Democrats and from some Republicans as well. But lawmakers at both congressional sessions expressed frustration that Rosenstein would say little in answer to their questions about his actions — or others' — before Comey's firing.

"There was considerable frustration in the room," said Rep. Seth Moulton, D-Mass., a member of the Armed Services Committee. "This renewed my confidence that we should not have confidence in this administration. I don't think (Rosenstein) did a lot to bolster our confidence in him today."

The White House has struggled since Comey's firing to explain the chain of events that led to it and the Justice Department's involvement in that decision. Trump has insisted at times that the decision was his alone, but he also has pointed to the "very strong" recommendation from Rosenstein.

Rosenstein made it clear to the lawmakers that he drafted his memo only after Trump told him of his plans to dismiss the FBI director. "My memorandum is not a statement of reasons to justify a for-cause termination," he said. But he added, "I wrote it. I believe it. I stand by it."

The memo focused on Comey's handling of the Hillary Clinton email investigation, particularly the FBI director's decision to divulge details to the public at various junctures during her presidential campaign against Trump. Rosenstein denounced that decision as "profoundly wrong and unfair."

Trump has reacted furiously to the appointment of a special counsel, a prosecutor with wide authority to investigate Russia's interference and other potential crimes uncovered. However, at a combative news conference Thursday, he fell short in trying to resolve questions about investigations into his campaign and his first four months in office.

Asked point-blank if he'd done anything that might merit prosecution or even impeachment, Trump said no — and then added of the lingering allegations and questions: "I think it's totally ridiculous. Everybody thinks so."

Associated Press writers Matthew Daly, Richard Lardner, Stephen Ohlemacher, Andrew Taylor, Kevin Freking, Mary Clare Jalonick, Eric Tucker and Deb Riechmann contributed to this report.