Acting Attorney General Mark Whitaker, named to head the Justice Department after Jeff Sessions was fired Wednesday, has a close relationship with President Trump and has expressed hostility toward special counsel Robert Mueller’s probe—which he may now oversee.

“Whitaker is on record as being more interested in propping up Trump than in upholding the rule of law,” one DOJ trial attorney told The Daily Beast. “It’s hard to have confidence that he’ll do anything other than what the president had said in his tweets.”

It’s been a meteoric rise for the 48-year-old Republican, an ex-prosecutor and failed political candidate who less than two years ago was the head of a little-known conservative nonprofit with designs on a judgeship in his home state of Iowa.

Through that nonprofit, and with the help of a PR firm later tied to a bizarre conspiracy theory, Whitaker ran interference for Sessions at one of the most fraught moments in his tumultuous time as attorney general.

In March 2017, The Washington Post reported that Sessions had neglected to tell the Senate at his confirmation hearing about prior conversations he had with the Russian ambassador.

The attorney general came under blistering criticism, especially as he had not yet recused himself from supervising the FBI’s investigation into Russian meddling in the 2016 election.

Then Whitaker spoke up. As executive director of the Foundation for Accountability and Civic Trust, an organization that served primarily to level ethics complaints against Democrats, he released a statement defending Sessions.

“If we are going to have a national discussion about Senators meeting with ambassadors it is appropriate for all Senators to disclose who they met with so the public, and apparently the media, understand that all Senator Sessions did was his job,” Whitaker said in the statement.

The statement was blasted out to reporters by CRC Public Relations, a conservative group based in Alexandria, Virginia, which represented FACT and Whitaker throughout 2017, according to press releases.

More recently, CRC faced scrutiny and criticism during Justice Brett Kavanaugh’s confirmation process for reportedly stoking media interest in a discredited conspiracy theory about Kavanaugh’s chief accuser.

Two people familiar with CRC’s communications at the time told The Daily Beast that people at the firm tipped off reporters that conservative activist Ed Whelan would be tweeting interesting material relevant to Kavanaugh’s confirmation.

Whelan then posted a tweetstorm claiming that Dr. Christine Blasey Ford, who had accused Kavanaugh of sexual assault, mistook him for a similar-looking high school classmate. Whelan, who even posted house blueprints and yearbook photos to support his theory, later had to apologize for accusing the other man of sexual assault.

By then, Whitaker had left FACT and become Sessions’ chief of staff.

At Justice, Whitaker was seen as Sessions’ right-hand man but often disagreed with the now former attorney general on a range of policy issues, according to two current DOJ officials.

Integral to the day-to-day operations of the department, Whitaker sat in on most high-level meetings and frequently visited the White House, where he developed a close rapport with Trump, according to more than half a dozen current and former officials in the department.

Whitaker and Sessions often disagreed on policy matters, officials said, and sparred in particular over the chief of staff’s increasingly close relationship with Trump and his staff.

In his new role, Whitaker is poised to assume oversight of special counsel Robert Mueller’s probe from Deputy Attorney General Rod Rosenstein. That’s raised questions about whether Whitaker might interfere with the probe, which is investigating Russian interference in the 2016 election and possible coordination with the Trump campaign.

“ We have had so many leaks from everywhere, including the Mueller team and those in the Department of Justice, that I think we would know if there was a smoking gun or any gun or any smoke. ” — Matthew Whitaker

Whitaker has previously expressed serious reservations about the Mueller probe, criticizing its direction in numerous cable news interviews over the past year.

He has called the investigation a drain on the department’s resources and claimed Mueller’s team leaked information to make the special counsel “look productive and on top of things.”

“We have had so many leaks from everywhere, including the Mueller team and those in the Department of Justice, that I think we would know if there was a smoking gun or any gun or any smoke,” he said in an August 2017 radio interview.

In a radio interview in May 2017, he described former Trump national security adviser Michael Flynn’s phone calls with the Russian ambassador during the presidential transition as potentially “friendly get-to-know-you” conversations. Flynn pleaded guilty to lying to the feds two months later.

In July 2017, Whitaker tweeted that it would be a “mistake” for Congress to pass legislation to protect Mueller from the White House, claiming Mueller was “already protected enough.”

A month later, he wrote an op-ed for CNN saying the Mueller investigation had gone too far.

“It does not take a lawyer or even a former federal prosecutor like myself to conclude that investigating Donald Trump’s finances or his family’s finances falls completely outside of the realm of his 2016 campaign and allegations that the campaign coordinated with the Russian government or anyone else,” Whitaker wrote. “That goes beyond the scope of the appointment of the special counsel.”

Whitaker, who is from Iowa, played football for the University of Iowa and graduated from its law school. He started his career in politics in 2002, when he ran unsuccessfully for Iowa state treasurer. Whitaker later headed Minnesota Gov. Tim Pawlenty’s presidential bid in Iowa before working as the state co-chairman of Texas Gov. Rick Perry’s 2012 White House bid.

In 2014, Whitaker unsuccessfully sought the Republican nomination for a U.S. Senate seat that was won by Joni Ernst. That same year, he was the chairman of Sam Clovis’ campaign for Iowa state treasurer. Clovis, whom Mueller’s team questioned last year, is the former Trump campaign official who oversaw George Papadopoulos, an aide who pleaded guilty to lying to investigators about his contact with individuals tied to Russia in 2016.

In the years after Whitaker ran for Senate, he built up his political connections, often meeting with influential lawmakers and think-tank leaders, two individuals who worked alongside him in the Department of Justice said.

St. John’s University law professor John Q. Barrett said he met Whitaker several times in the “green room” at CNN when both were appearing to discuss Mueller’s investigation.

He said Whitaker told him he was shuttling back and forth to New York to raise his profile in the hopes the White House would notice him.

“I said, ‘What are you interested in? And he said, ‘A judgeship,’” Barrett said, adding that he got the impression he wanted an appointment in Iowa.

A few months later, Whitaker became chief of staff to Sessions. “I guess something led to something,” Barrett said.

Whitaker’s TV appearances were in his role as head of FACT. The organization’s funding is opaque: In 2014, it received $600,000 from a fund called DonorsTrust, whose donors are mostly anonymous, but for Charles Koch. But in 2016, Open Secrets could only find one example of FACT targeting a Republican.

At FACT, Whitaker often accused Hillary Clinton of ethics violations, and in 2017, said he believed her handling of classified emails amounted to a “strong” case against her.

“She should be extremely grateful that has not happened,” Whitaker said.

Despite his ambition, those close to him say Whitaker was approachable and collaborative, even if they had different political views.

“My impression of Matt is that he is a very normal guy,” said one former official from the Department of Justice. “He is a pretty nice way about him.”

“ Matt is a conservative Republican. That is who he is. No doubt about that. ” — Former U.S. Attorney

Whitaker is also known for his deeply conservative views of the law. He wrote several opinion pieces in the national media, including one that said he would have indicted Clinton for her emails. In an interview while campaigning in Iowa, he said he thought Marbury vs. Madison—a landmark decision that gives courts the power to declare legislative and executive acts unconstitutional—was a “bad ruling.”

“Matt is a conservative Republican. That is who he is. No doubt about that,” said one former U.S. attorney who has known Whitaker for years.

Whitaker’s appointment follows months of speculation that Trump was set to make major changes in his Cabinet after the midterms. Trump has become increasingly frustrated with Justice and Mueller.

Over the past year, he has repeatedly mused to lawyers, confidants, and West Wing aides about his desire to sack Sessions, whom he felt failed to protect him from the Russia probe.

Sessions indicated he wanted to stay at Justice, writing to Trump, “At your request, I am submitting my resignation.” The White House didn’t respond to questions on why Trump and his team are not saying Sessions was fired.

Justice Department staffers gathered in the courtyard Wednesday to say goodbye to Sessions as he left the office for the last time. Whitaker shook his predecessor’s hand before Sessions was driven off amid a standing ovation.