The former acting AG testified that Trump had not tried to intervene in the investigation… How do you suppose the man that tried to market a toilet for “well endowed men” will hold up under Mueller’s questioning?

As federal prosecutors in Manhattan gathered evidence late last year about President Trump’s role in silencing women with hush payments during the 2016 campaign, Mr. Trump called Matthew G. Whitaker, his newly installed attorney general, with a question. He asked whether Geoffrey S. Berman, the United States attorney for the Southern District of New York and a Trump ally, could be put in charge of the widening investigation, according to several American officials with direct knowledge of the call.

Mr. Whitaker, who had privately told associates that part of his role at the Justice Department was to “jump on a grenade” for the president, knew he could not put Mr. Berman in charge because Mr. Berman had already recused himself from the investigation. The president soon soured on Mr. Whitaker, as he often does with his aides, and complained about his inability to pull levers at the Justice Department that could make the president’s many legal problems go away.

Trying to install a perceived loyalist atop a widening inquiry is a familiar tactic for Mr. Trump, who has been struggling to beat back the investigations that have consumed his presidency. His efforts have exposed him to accusations of obstruction of justice as Robert S. Mueller III, the special counsel, finishes his work investigating Russian interference in the 2016 election.

Mr. Trump’s public war on the inquiry has gone on long enough that it is no longer shocking. Mr. Trump rages almost daily to his 58 million Twitter followers that Mr. Mueller is on a “witch hunt” and has adopted the language of Mafia bosses by calling those who cooperate with the special counsel “rats.” His lawyer talks openly about a strategy to smear and discredit the special counsel investigation. The president’s allies in Congress and the conservative news media warn of an insidious plot inside the Justice Department and the F.B.I. to subvert a democratically elected president.

An examination by The New York Times reveals the extent of an even more sustained, more secretive assault by Mr. Trump on the machinery of federal law enforcement. Interviews with dozens of current and former government officials and others close to Mr. Trump, as well as a review of confidential White House documents, reveal numerous unreported episodes in a two-year drama.

Mr. Whitaker, who this month told a congressional committee that Mr. Trump had never pressured him over the various investigations, is now under scrutiny by House Democrats for possible perjury.

On Tuesday, after The Times article published, Mr. Trump denied that he had asked Mr. Whitaker if Mr. Berman could be put in charge of the investigation. “No, I don’t know who gave you that, that’s more fake news,” Mr. Trump said. “There’s a lot of fake news out there. No, I didn’t.”