Rep. Eliot Engel (D-NY), chairman of the House Foreign Affairs Committee, alleges that former White House National Security Advisor John Bolton hinted to him in September to look into the removal of former U.S. Ambassador to Ukraine Marie Yovanovitch.

In a Wednesday statement, Engel said Bolton called him on September 19, roughly one week after he was fired from his post, and inferred wrongdoing was involved in the ambassador’s ouster.

“He and I spoke by telephone on September 23. On that call, Ambassador Bolton suggested to me — unprompted — that the committee look into the recall of Ambassador Marie Yovanovitch,” said the New York Democrat. “He strongly implied that something improper had occurred around her removal as our top diplomat in Kyiv.”

The timeline of the ongoing impeachment proceedings shows that House Speaker Nancy Pelosi announced a formal inquiry to remove the president just one day after the purported Engel-Bolton conversation.

Engel’s statement follows a New York Times report alleging that Bolton’s forthcoming book — The Room Where It Happened: A White House Memoir — includes a passage claiming that President Trump sought to link $400 million in U.S. security aid to Ukraine and investigations into former Vice President and 2020 Democrat contender Joe Biden, and his son, Hunter Biden.

President Trump vehemently rebuked the purported claims, calling them unequivocally “false.”

Earlier Wednesday, the president slammed his former national security advisor for writing a “nasty & untrue book” about his time in the White House.

“For a guy who couldn’t get approved for the Ambassador to the U.N. years ago, couldn’t get approved for anything since, ‘begged’ me for a non Senate approved job, which I gave him despite many saying ‘Don’t do it, sir,’ takes the job, mistakenly says ‘Libyan Model’ on T.V., and many more mistakes of judgement [sic], gets fired because frankly, if I listened to him, we would be in World War Six by now, and goes out and IMMEDIATELY writes a nasty & untrue book. All Classified National Security. Who would do this?” tweeted the president.

Meanwhile, the National Security Council, which has been tasked with reviewing Bolton’s manuscript, has requested that he remove all present classified information before its March 17 release date.

“Under federal law and the nondisclosure agreements your client signed as a condition for gaining access to classified information, the manuscript may not be published or otherwise disclosed without the deletion of this classified information,” Ellen Knight, the NCS’s Senior Director for Records, Access, and Information Security Management, wrote in a letter to Bolton lawyer Charles Cooper.

The development has landed Bolton at the center of the Senate’s impeachment trial, with upper chamber Democrats demanding that he testify.

“This is stunning,” Schumer said in a Monday press conference, addressing the purported revelations. “It goes right to the heart of the charges against the president. Ambassador Bolton essentially confirms the president committed the offenses charged in the first article of impeachment.”

However, some top Republicans have said Bolton’s allegations are insignificant.

“There’s nothing new here. It does seem to be an effort to sell books,” Sen. John Barrasso (R-WY) said Monday.

“The basic dynamic of the obligation of the House to take the time they have to put a case together doesn’t change,” Sen. Roy Blunt (R-MO) added. “I don’t think it changes any fundamental information, nor does it change the basic case that the House has to put the case together.”