Rosenstein talked about secretly recording the president using a wire in May 2017, memos written by then-acting FBI Director Andrew McCabe and FBI lawyer Lisa Page said, according to a Washington Post report. Rosenstein also brought up the 25th Amendment, which allows a president to be removed from office when no longer able to discharge duties.
The revelations, first reported in The New York Times, suggested Rosenstein was concerned in spring 2017 over a memo he wrote about then-FBI director James Comey, which was critical of his handling of Hillary Clinton's email investigation, that Trump used to rationalize firing Comey.
Rosenstein denied the accuracy of the Times report, but the revelations have sparked speculation about whether Trump will use this information to fire Rosenstein.
Rosenstein, as deputy attorney general, oversees special counsel Robert Mueller's investigation into Russian interference in the 2016 election and whether the president and his associates played a role in that effort.
Friday evening at a Springfield, Mo., rally Trump weighed in on how he felt about the FBI in light of the news.
"Look at what's being exposed at the Department of Justice and the FBI. We have great people in the Department of Justice ... but we have some real bad ones," Trump said. "You see what's happening at the FBI, they're all gone, they're all gone. But there's a lingering stench and we're going to get rid of that, too."