WASHINGTON — Acting Attorney General Matthew Whitaker's "decision not to recuse himself from the special counsel's investigation" was made against the advice he was given by Justice Department ethics officials, Senate leaders were informed on Thursday.

The Department of Justice's senior career ethics official told the senior staff of the Justice Department that ethics officials "would advise" that Whitaker recuse himself if asked, the letter obtained by BuzzFeed News detailed.

Specifically, the ethics official advised that Whitaker's oversight of the special counsel's investigation could "raise an appearance-of-impartiality issue" due to his past comments critical of special counsel Robert Mueller's investigation.

Whitaker was informed of that view but nonetheless decided not to recuse himself, the letter from Stephen Boyd, the assistant attorney general for DOJ's Office of Legislative Affairs, stated.

The "ultimate decision" on recusal "in a case such as this rests with the Acting Attorney General," the letter, sent to Senate Majority Leader Mitch McConnell and Minority Leader Chuck Schumer, said.

The letter goes on to state that Whitaker made the decision after considering "all relevant views" and based, in part, on the fact that no prior attorney general had recused themselves due to "appearance-of-impartiality" grounds based on prior statements.

In total, Boyd's letter provides a numbered list of seven reasons why Whitaker chose not to recuse himself, one of which was that "on multiple previous occasions" Whitaker had said nice things about Mueller, including that Mueller is "a professional" and "a good man."

Congressional leaders, outside ethics organizations, and news organizations had been seeking information from the Justice Department about the recusal question since the days after Trump announced via Twitter that Whitaker would be the acting attorney general — taking over for ex-attorney general Jeff Sessions, who was forced out of the job by Trump on the Wednesday after the midterm elections.

The weekend after Whitaker, who had previously served as Sessions' chief of staff, took over as acting attorney general, Justice Department spokesperson Kerri Kupec emailed, "Acting AG Whitaker is fully committed to following all processes and procedures of the Department of Justice, including meeting with ethics officials on his oversight responsibilities, matters that may warrant recusals, etc."

Several outlets reported earlier Thursday that the decision had been made against recusal, citing sources familiar with the decision.

The recusal decision comes even as litigation over the legality and constitutionality of Trump's decision to appoint Whitaker to the role of acting attorney general is ongoing.

Trump has said that William P. Barr, the attorney general in the George H.W. Bush administration, is his pick to be nominated to be the next attorney general and Whitaker has submitted paperwork to the Senate Judiciary Committee. The nomination itself has not yet been sent to the Senate, but it is expected to be submitted at the start of the new session of Congress in January.

Until a successor is actually confirmed, however, Whitaker appears poised (outside of the court challenges) to remain at the helm of the Justice Department for the time being.