Donald Trump and James Comey. Getty Images President Donald Trump told two Russian diplomats in an Oval Office meeting last week that by firing "nut job" FBI Director James Comey, he had taken "great pressure" off of himself, The New York Times reported on Friday.

Comey, who was leading an FBI investigation into Trump's campaign team and whether it colluded with the Kremlin during the 2016 election, was fired earlier this month. The next day, Trump met with Russian Foreign Minister Sergey Lavrov and Ambassador Sergey Kislyak.

Trump's comments last week and in February — when he reportedly nudged Comey to drop the bureau's investigation into Michael Flynn, the former national security adviser — have led lawmakers and legal experts to question whether Trump sought to obstruct justice, a criminal and impeachable offense.

"Telling the Russians — the adversary at issue the investigation itself — that firing Comey would ease pressure is compelling evidence of corrupt intent under normal circumstances," said Andrew Wright, an associate professor at Savannah Law School who specializes in federal criminal law and national security. "Many a criminal defendant have gotten convicted on evidence of their intent just like that."

Jeffrey Toobin, a CNN legal analyst, said Trump's reported comments were "close to a confession of obstruction of justice."

Obstruction of justice is broadly defined: It involves any conduct in which a person willfully interferes with the administration of justice. The FBI's investigation has progressed in recent weeks, and McClatchy reported on Friday that Congress was told it now included whether any Trump officials engaged in a cover-up.

The White House press secretary, Sean Spicer, said in a statement on Friday that "by grandstanding and politicizing the investigation into Russia's actions, James Comey created unnecessary pressure on our ability to engage and negotiate with Russia. The investigation would have always continued, and obviously, the termination of Comey would not have ended it."

He added, "Once again, the real story is that our national security has been undermined by the leaking of private and highly classified conversations."

But Trump's conversations with Comey and the Russians were part of a pattern that could open him up to charges of obstruction of justice, experts say. That pattern begins with Trump's reported requests for Comey to pledge his loyalty and assurance that he wasn't under FBI investigation and ends when he fired Comey and criticized him in front of the Russians.

"Historically, obstruction-of-justice articles of impeachment do elaborate a pattern of conduct," legal experts at Lawfare wrote earlier this week.

"The first article of impeachment against Richard Nixon, for instance, included making false statements to investigators, withholding evidence, counseling witnesses to lie or give misleading testimony, and 'interfering or endeavoring to interfere with the conduct of investigations by the Department of Justice of the United States and the Federal Bureau of Investigation.'"

Moreover, Trump reportedly has kept in touch with at least one former associate who is under active criminal investigation by the FBI.

"I just got a message from the president to stay strong," Flynn told his friends at a restaurant in northern Virginia late last month, according to Yahoo News.