The top Democrat on the House Judiciary Committee, Rep. Jerrold Nadler (N.Y.), warned on Wednesday that any attempt by President Trump Donald John TrumpSteele Dossier sub-source was subject of FBI counterintelligence probe Pelosi slams Trump executive order on pre-existing conditions: It 'isn't worth the paper it's signed on' Trump 'no longer angry' at Romney because of Supreme Court stance MORE to fire Deputy Attorney General Rod Rosenstein Rod RosensteinDOJ kept investigators from completing probe of Trump ties to Russia: report Five takeaways from final Senate Intel Russia report FBI officials hid copies of Russia probe documents fearing Trump interference: book MORE would be a step toward a "long drawn out Saturday Night Massacre."

"His firing would be another step in a pattern of obstruction of justice, and that obstruction of justice will have to be looked at very carefully. Whether it's grounds for impeachment remains to be seen," Nadler told Hill.TV's Krystal Ball and Buck Sexton on "Rising."

"Right now, all one has to say is that the investigation must continue and must be protected," he added. "Its integrity must be protected, and any attempt to [fire] Rosenstein, would be another step in a long drawn out Saturday Night Massacre."

The so-called Saturday Night Massacre took place in 1973 when then-President Nixon fired the special prosecutor leading the Watergate investigation, a move that prompted the resignation of the attorney general and deputy attorney general.

The New York Times reported last week that Rosenstein had talked about wearing a wire to secretly record his conversations with Trump. He also reportedly discussed efforts to invoke the 25th Amendment, which lays out steps for removing a president from office.

Rosenstein called the Times article "factually incorrect," and some officials defending Rosenstein said his comments were made in jest.

Trump said at a press conference in New York on Wednesday that it was not his preference to fire Rosenstein.