Matthew Whitaker, President Donald Trump’s pick to replace ousted former Attorney General Jeff Sessions, has come under fire for his objections to investigating the president, his suspicious business history and his possible legal violations.

Whitaker’s past raises serious questions about his eligibility to oversee special counsel Robert Mueller’s investigation into possible Trump campaign ties to Russian interference in the 2016 elections ― let alone his qualifications to be the country’s chief legal principal.

Here are five of the biggest issues with Whitaker taking over as acting attorney general.

He raked in over a million dollars leading a “charity” with no employees.

Whitaker collected more than $1.2 million as the leader of the Foundation for Accountability and Civic Trust (FACT), a group that described itself as a charitable nonprofit dedicated to “promoting accountability, ethics, and transparency in government and civic arenas,” though it largely worked to promote conservative causes.

The Washington Post first reported on Whitaker’s massive financial gains leading the mysterious group, collected in the three years after he arrived in Washington, D.C., in 2014. FACT’s origins and funding remain obscure, and the group had no employees aside from Whitaker and existed only on paper, the Post said Tuesday.

“It’s very possible that this organization is misusing its status as a charity,” David Nelson, a specialist on nonprofit organizations who reviewed FACT’s tax filings for the Post, told the paper. “It appears the IRS never gave approval to FACT.”

He may have broken the law by receiving political donations.

On Wednesday, the political watchdog group American Oversight called on the Office of Special Counsel to investigate Whitaker for possible violations of the Hatch Act, which restricts political activities by federal employees.

The complaint cites several political donations Whitaker received while serving as chief of staff and senior counselor in Session’s office, according to his financial disclosure forms. In one example, the complaint notes that Whitaker’s 2014 U.S. Senate campaign committee is still active and that he received four political contributions totaling $8,800 between Jan. 29 and Feb. 22 of this year.

“The nation’s highest law enforcement officer should be above reproach, but Acting Attorney General Whitaker’s financial disclosures raise potential concerns of both dishonesty and covert partisan conflicts of interest,” Austin Evers, American Oversight’s executive director, said in a statement.

The filings also show that Whitaker revised his financial disclosure forms at least five times after he submitted them, HuffPost noted Tuesday.

AP Photo/Mary Altaffer Acting Attorney General Matthew Whitaker, framed by a photograph of lower Manhattan, addresses law enforcement officials at the Joint Terrorism Task Force on Nov. 21, 2018, in New York.

It may not be constitutional for him to act as attorney general.

Several Democrats and legal scholars have argued that Trump’s appointment of Whitaker as acting attorney general isn’t legitimate.

On Monday, Sens. Richard Blumenthal (D-Conn.), Mazie K. Hirono (D-Hawaii) and Sheldon Whitehouse (D-R.I.) filed a lawsuit calling into question Whitaker’s eligibility to take on the role without being in another Senate-confirmed position at the time of his appointment, as all acting attorney generals in the past have been.

The Justice Department’s Office of Legal Counsel issued a 20-page opinion last week arguing that Whitaker’s appointment is lawful.

Upon Sessions’ forced resignation, several prominent legal scholars wrote in a New York Times op-ed that Whitaker’s appointment was unconstitutional under the Appointments Clause, given that the role of attorney general is a “principal” position requiring Senate confirmation.

He’s already taken a side in an investigation he should be impartial on.

In a conflict of interest that’s most certainly not lost on Trump, Whitaker has been openly critical of Mueller’s investigation into the Trump campaign ― an investigation he now oversees until Trump taps a permanent replacement.

Whitaker rose to prominence as a contributor on CNN, where he was best known for railing against the Mueller investigation. He insisted on air that nothing would come of it, that Mueller’s budget should be capped, that Donald Trump Jr. was not in the wrong for meeting with a Russian lawyer to talk about Hillary Clinton and that investigating the Trump Organization’s financial ties to Russia crossed a “red line.”

In a CNN editorial published earlier this month, Whitaker argued that Mueller’s probe could become “a mere witch hunt.”

“Mueller has come up to a red line in the Russia 2016 election-meddling investigation that he is dangerously close to crossing,” Whitaker wrote.

He’s friends with one of Mueller’s grand jury witnesses.

In another conflict of interest, Whitaker has a close friendship with Sam Clovis, Trump’s 2016 election campaign co-chair who has testified before the grand jury in the Mueller investigation.

Clovis has said he and Whitaker became close when they ran against each other in a 2014 Senate primary campaign in Iowa. Whitaker eventually went on to serve as the chairman of Clovis’ campaign for state treasurer.

Walter Shaub, who served as director of the U.S. Office of Government Ethics until resigning in July of last year, told Reuters that their relationship should disqualify Whitaker from overseeing Mueller’s investigation.

“Whitaker has to recuse himself under DOJ’s regulation requiring recusal if you have a personal or political relationship with someone substantially involved in conduct that is the subject of the investigation or prosecution,” Shaub said.