Attorney General Jeff Sessions is out, and President Donald Trump has named Matthew Whitaker as his replacement — giving a man who once suggested special counsel Robert Mueller’s investigation was a “witch hunt” control of the fate of the probe.

Whitaker served as Sessions’s chief of staff, one of the most powerful positions at the Justice Department. The deputy attorney general, Rod Rosenstein, would typically be tapped to take over in an acting role, but Trump chose Whitaker instead.

Even though he will be serving in an acting capacity, Whitaker is now expected to oversee the Mueller probe, so long as he doesn’t have any conflicts that would force him to recuse himself. He will have the power to let Mueller keep doing what he’s doing — or curtail or shut down the investigation altogether.

Whitaker’s name first cropped up in September as a potential acting replacement for Rosenstein, who appeared to be on the verge of getting fired himself.

Whitaker seemed like a curious choice at the time. Trump has repeatedly and publicly chastised Sessions, mostly for recusing himself from overseeing the Mueller probe. Putting a Sessions ally in the second most powerful position at the Justice Department, then, seemed odd.

The question now is why would Trump tap him to take over temporarily for Sessions. The answer could lie in Whitaker’s past criticism of the Mueller probe and one of the president’s favorite foils: former Secretary of State Hillary Clinton.

Why Trump may have chosen Whitaker

Whitaker, a former US attorney from Iowa, is the White House’s “eyes and ears” in the Justice Department, according to the New York Times. He’s also a fiscal and social conservative who unsuccessfully ran for Senate in 2014. He aligns with Trump (and Sessions) when it comes to issues like crime and immigration, but Whitaker comes with the added perk (for Trump) of having publicly criticized Mueller.

For example, Whitaker expressed skepticism about the Mueller probe before joining the Trump administration as Session’s chief of staff in the fall of 2017.

And in August 2017, in an op-ed for CNN, Whitaker blasted Mueller’s investigation.

“Mueller has come up to a red line in the Russia 2016 election-meddling investigation that he is dangerously close to crossing,” Whitaker wrote. “If he were to continue to investigate the [Trump family’s] financial relationships without a broadened scope in his appointment, then this would raise serious concerns that the special counsel’s investigation was a mere witch hunt.”

Though there was no public evidence that Rosenstein had declined any significant Mueller request, Whitaker argued that Rosenstein had to limit the scope of Mueller’s probe — the very investigation Whitaker is poised to inherit.

And in a CNN appearance in July 2017, Whitaker offered his own take on how an acting attorney general could sideline Mueller.

“I could see a scenario where Jeff Sessions is replaced with a recess appointment,” Whitaker said, “and that attorney general doesn’t fire Bob Mueller, but he just reduces his budget to so low that his investigation grinds to almost a halt.”

Beyond his scrutiny of Mueller, Whitaker has also publicly lambasted Hillary Clinton, the former secretary of state and Trump’s former election opponent.

While serving as head of the Foundation for Accountability and Civic Trust, a right-leaning organization that criticizes Democrats on ethics matters, Whitaker said in May 2017 that Clinton should be “extremely grateful” she wasn’t prosecuted for having a private email server.

Three months later, he wrote for the Hill that Clinton’s connections to Ukraine were “worth exploring.”

The Justice Department confirmed Wednesday in a statement emailed to reporters that Whitaker is in charge of all matters under the department’s purview. However, HuffPost’s Ryan J. Reilly reported that DOJ ethics officials haven’t examined whether Whitaker would have to recuse himself from overseeing the Russia investigation because of his prior comments.

Some Democrats, including Minority Leader Chuck Schumer, have already called on Whitaker to recuse himself altogether, but there’s no sign yet that that is going to happen.