President Donald Trump took his fight with the FBI to a new level, raising the specter Friday that he may have taped his conversations with Director James Comey before firing him.

In a morning post on Twitter, Trump said Comey "better hope that there are no 'tapes,'" raising a question about whether Trump is recording key conversations.

James Comey better hope that there are no "tapes" of our conversations before he starts leaking to the press! — Donald J. Trump (@realDonaldTrump) May 12, 2017

The warning followed Trump calling Comey a "showboat" and a "grandstander" Thursday and insisting the bureau's Russia probe would show he did nothing wrong.

He said he'd sent a letter to a top Republican lawmaker declaring he has no business dealings there.

Yet try as he might, Trump cannot escape Russia as congressional probes push ahead and the nation's top law-enforcement agency shows no sign of backing down in the face of the president's criticism.

Comey's temporary replacement, Andrew McCabe, made clear that he liked and respected Comey, had no intention of briefing Trump on the investigation into possible ties between Russia and Trump's campaign as long as he held the job and considered it one of the most important probes underway at the Justice Department.

McCabe, a 21-year-veteran of the bureau, made an effort during Senate testimony Thursday to dispute White House assertions that his former boss had lost the trust of FBI rank-and-file.

"Director Comey enjoyed broad support in the FBI and still does to this day," McCabe said Thursday before the Senate Intelligence Committee. He said that working with Comey was "the greatest privilege and honor of my professional life."

The clash between the president and the nation's premier law enforcement agency continued a week of high drama in Washington. Fired Acting Attorney General Sally Yates testimony May 8 raised new questions about why the White House waited 18 days to dismiss National Security Advisor Michael Flynn from his post after he misled officials -- including Vice President Mike Pence -- about his conversations with Russia's ambassador to the U.S.

Trump's justifications for dismissing Comey have raised key questions about possible politicization of law enforcement. In a May 9 letter to Comey, Trump said the director had on three occasions assured him that he wasn't under investigation. If true, that would be a breach of FBI norms against discussing ongoing cases.

This report contains material from Bloomberg News.