WASHINGTON (AP) - Fellow Republicans pressed President Donald Trump on Sunday to come clean about whether he has tapes of private conversations with former FBI Director James Comey and provide them to Congress if he does - or possibly face a subpoena, as a Senate investigation into collusion with Russia or obstruction of justice extended to a Trump Cabinet member.

It was a sign of escalating fallout from riveting testimony from Comey last week of undue pressure from Trump, which drew an angry response from the president on Friday that Comey was lying.

Attorney General Jeff Sessions was in for sharp questioning by senators on the Senate Intelligence committee Tuesday. Whether that hearing will be public or closed is not yet known.

"I don't understand why the president just doesn't clear this matter up once and for all," said Sen. Susan Collins, R-Maine, a member of that committee, referring to the existence of any recordings.

She described Comey's testimony as "candid" and "thorough" and said she would support a subpoena if needed. Trump "should voluntarily turn them over," Collins said.

Sen. James Lankford, R-Okla., also a member of that committee, agreed the panel needed to hear any tapes that exist. "We've obviously pressed the White House," he said.

Trump's aides have dodged questions about whether conversations relevant to the Russia investigation have been recorded, and so has the president. Pressed on the issue Friday, Trump said "I'll tell you about that maybe sometime in the very near future."

Lankford said Sessions' testimony Tuesday will help flesh out the truth of Comey's allegations, including Sessions' presence at the White House in February when Trump asked to speak to Comey alone. Comey alleges that Trump then privately asked him to drop a probe into former national security adviser Michael Flynn's contacts with Russia.

Comey also has said Sessions did not respond when he complained he didn't "want to get time alone with the president again." The Justice Department has denied that, saying Sessions stressed to Comey the need to be careful about following appropriate policies.

"We want to be able to get his side of it," Lankford said.

Sen. Jack Reed, D-R.I., said "there's a real question of the propriety" of Sessions' involvement in Comey's dismissal, because Sessions had stepped aside from the federal investigation into contacts between Russia and the Trump campaign. Comey was leading that probe.

Reed said he also wants to know if Sessions had more meetings with Russian officials as a Trump campaign adviser than have been disclosed.

Trump on Sunday accused Comey of "cowardly" leaks and predicted many more from him. "Totally illegal?" he asked in a tweet. "Very 'cowardly!'"

Several Republican lawmakers also criticized Comey for disclosing memos he had written in the aftermath of his private conversations with Trump, calling that action "inappropriate." But, added Lankford "releasing his memos is not damaging to national security."

The New York City federal prosecutor who expected to remain on the job when Trump took office but ended up being fired said he was made uncomfortable by one-on-one interactions with the president - just like Comey was. Preet Bharara told ABC's "This Week" that Trump was trying to "cultivate some kind of relationship" with him when he called him twice before the inauguration to "shoot the breeze."

He said Trump reached out to him again after the inauguration but he refused to call back, shortly before he was fired.

On Comey's accusations that Trump pressed him to drop the FBI investigation of Flynn, Bharara said "no one knows right now whether there is a provable case of obstruction" of justice. But: "I think there's absolutely evidence to begin a case."

Democratic Sen. Dianne Feinstein of California, a member of the Intelligence committee, sent a letter to Sen. Chuck Grassley, R-Iowa, urging him to investigate possible obstruction of justice by Trump in Grassley's position as chairman of the Judiciary Committee. Feinstein is the top Democrat on that panel and a member of both.

She said Sessions should also testify before the Judiciary Committee, because it was better suited to explore legal questions of possible obstruction. Feinstein said she was especially concerned after National Intelligence Director Dan Coats and National Security Agency Director Michael Rogers refused to answer questions from the intelligence committee about possible undue influence by Trump.

Feinstein said she did not necessarily believe Trump was unfit for office, as House Democratic leader Nancy Pelosi has asserted, but said he has a "destabilizing effect" on government.

"There's an unpredictability. He projects an instability," Feinstein said. "Doing policy by tweets is really a shakeup for us, because there's no justification presented."

In other appearances Sunday:

-Senate Democratic leader Chuck Schumer of New York said he would take Trump up on his offer to testify under oath about his conversations with Comey, inviting the president to testify before the Senate.

-Feinstein acknowledged she "would have a queasy feeling, too" if Comey's testimony was true that Loretta Lynch, as President Barack Obama's attorney general, had directed him to describe the FBI probe into Hillary Clinton's email practices as merely a "matter" and to avoid calling it an investigation. Feinstein said the Judiciary Committee should investigate.

Sessions stepped aside in March from the federal investigation into contacts between Russia and the campaign after acknowledging that had met twice last year with the Russian ambassador to the U.S. He had told lawmakers at his January confirmation hearing that he had not met with Russians during the campaign.

Sessions has been dogged by questions about possible additional encounters with the ambassador, Sergey Kislyak.

As for the timing of Sessions' recusal, Comey said the FBI expected the attorney general to take himself out of the matters under investigation weeks before he actually did.

Collins and Feinstein spoke on CNN's "State of the Union and Lankford and Schumer appeared on CBS' "Face the Nation." Reed was on "Fox News Sunday."

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