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(CNN) —  

Deputy Attorney General Rod Rosenstein on Friday hailed acting Attorney General Matthew Whitaker as a “superb” choice to fill the role even as Whitaker’s past statements have prompted questions about his impartiality toward special counsel Robert Mueller’s investigation.

“I think he’s a superb choice for attorney general,” Rosenstein told a small group of reporters gathered outside of an investiture ceremony for US Attorney Zachary Terwilliger in Alexandria, Virginia. “He certainly understands the work, understands the priorities of the department.”

RELATED: Sessions replacement Matthew Whitaker called Mueller’s appointment ‘ridiculous’ and ‘a little fishy’

The positive tone from the No. 2 official at the Justice Department was notable, as Rosenstein and Whitaker have had a complicated relationship for some time, compounded by the fact that Whitaker had discussed taking Rosenstein’s job with President Donald Trump several weeks ago. Despite that, Rosenstein, who has weathered the President’s bad side at times and attacks from some of Trump’s most vocal Hill allies, has managed to survive, and he publicly praised Whitaker on Friday in a clear attempt at displaying department solidarity.

Whitaker, who previously served as chief of staff to Attorney General Jeff Sessions, was vaulted to the position of acting attorney general on Wednesday after Trump fired Sessions.

“We are pleased to announce that Matthew G. Whitaker, Chief of Staff to Attorney General Jeff Sessions at the Department of Justice, will become our new Acting Attorney General of the United States,” Trump said in a tweet. “He will serve our Country well.”

“We thank Attorney General Jeff Sessions for his service, and wish him well! A permanent replacement will be nominated at a later date,” he added.

Since the announcement, Whitaker has faced criticism for his past comments on Mueller’s investigation into Russian interference in the 2016 US election – an investigation he is expected to oversee as acting attorney general.

In 2017, Whitaker wrote a CNN op-ed that argued Mueller was “dangerously close to crossing” a red line following reports that the special counsel was looking into Trump’s finances, and he called the special counsel’s appointment “ridiculous” and “a little fishy” in a 2017 appearance on the “Rose Unplugged” radio program.

Rosenstein added Friday that he had delivered his message of praise for Whitaker on Thursday in a conference call with federal prosecutors around the country: “I think he’s going to do a superb job as attorney general.”

For nearly 18 months, Rosenstein has overseen the special counsel’s investigation because Sessions had stepped aside from all matters related to the presidential campaign.

When Whitaker leapfrogged over Rosenstein and was named acting attorney general, questions immediately began to swirl about who Mueller would report to, whether Whitaker must recuse himself from the investigation given his fierce criticism of it, whether Rosenstein would quit and whether Mueller’s work will be curtailed.

Whitaker has given no indication he believes he needs to step aside from ultimately overseeing Mueller’s investigation, one person familiar with his thinking told CNN on Thursday. That belief is echoed by White House officials who also do not believe Whitaker needs to recuse himself, sources tell CNN.

Rosenstein is expected to continue to handle the day-to-day management of the probe, as he would for any other significant criminal investigation.

However, the arrangement may prove challenging down the line, or quickly, if Whitaker and Rosenstein disagree on any significant matter.

As The Washington Post reported Thursday, people close to Whitaker do not believe he would approve Mueller seeking a subpoena of President Donald Trump.

CNN’s Kaitlan Collins, Betsy Klein, Pamela Brown, Evan Perez and Andrew Kaczynski contributed to this report.