Rep. Jason Chaffetz of Utah. Chip Somodevilla/Getty Images The House oversight committee chairman, Jason Chaffetz, said he had his "subpoena pen ready" Tuesday amid reports that James Comey kept memos while serving as FBI director of conversations with President Donald Trump — one of which reportedly said Trump asked Comey to drop an investigation into Michael Flynn, the ousted national security adviser.

In a tweet, Chaffetz said the House oversight committee was "going to get the Comey memo, if it exists."

"I need to see it sooner rather than later," he continued. "I have my subpoena pen ready."

On Tuesday night, The New York Times reported that an associate of Comey's had read aloud parts of a memo Comey had written saying Trump had asked Comey to shut down the FBI's investigation into Flynn, who was fired after misleading Vice President Mike Pence about his December conversations with Russia's ambassador to the US.

Top congressional officials have suggested the apparent request could be evidence that Trump tried to influence investigations by the Justice Department and the FBI into whether the Trump campaign colluded with Russian officials to meddle in the 2016 election.

"I hope you can see your way clear to letting this go, to letting Flynn go," Trump said, according to the memo cited in The Times. "He is a good guy. I hope you can let this go."

"On the surface that seems like an extraordinary use of influence to try to shut down an investigation being done by the FBI," said Chaffetz, according to NBC News' Alex Moe.

Chaffetz also wrote a letter to the FBI's acting director, Andrew McCabe, on Tuesday, saying, "If true, these memoranda raise questions as to whether the President attempted to influence or impede the FBI's investigation."

Chaffetz requested in his letter that by May 24 he receive all memoranda, notes, summaries, and recordings documenting interactions between Trump and Comey.

You can read Chaffetz's letter to the FBI »