Attorney General Jeff Sessions, one of President Donald Trump's earliest supporters, who once proudly referred to himself as a Trump "surrogate," announced his resignation on Wednesday. He will be replaced by a Trump loyalist who has questioned the scope of the Mueller probe in the past — and is now expected to oversee it.

In an undated letter to the president revealed Wednesday, Sessions wrote that he was submitting his resignation to Trump "at your request," indicating that he was effectively fired. Sessions' chief of staff, Matthew G. Whitaker, will immediately take over the role, thanks to a 1998 law that allows Trump to fill high-level vacancies on an acting basis with any Senate-confirmed official, a pool of potential candidates also rumored to include Deputy Attorney General Rod Rosenstein and Solicitor General Noel Francisco.

Whitaker has long been popular with the White House, where Trump's chief of staff John Kelly considered him the "White House's eyes and ears," at the Department of Justice, according to the New York Times. Now it seems likely Whitaker will transfer his gaze to the special investigation into Russian involvement in the Trump campaign.

As acting Attorney General, Whitaker will be "in charge of all matters under the purview of the Department of Justice," Justice Department spokesperson Sarah Flores said in a statement Wednesday.

But Whitaker isn't coming into the job an impartial observer — in fact, he has a number of potentially disqualifying statements that had some political analysts writing him off as a viable option to oversee the Mueller probe, back when Sessions' ouster was still a hypothetical.

In one July 2017 appearance on CNN, which took place before he was appointed Sessions’ chief of staff, Whitaker expressed skepticism about the integrity and validity of the Russia investigation.

“So 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.”

He's also argued the Mueller probe should not include the president's finances.

Minutes after the announcement Wednesday, Chuck Schumer, the Democratic Senate minority leader from New York, called for Whitaker to recuse himself from the investigation.

“Given his previous comments advocating defunding and imposing limitations on the Mueller investigation, Mr. Whitaker should recuse himself from its oversight for the duration of his time as acting attorney general,” Schumer said in a statement.

Trump's announcement came less than a day after the Democrats took control of the House of Representatives in the midterm elections, promising strenuous oversight over the president and his administration. Republicans, meanwhile, picked up at least four more Senate seats, ensuring an easy confirmation for whoever Trump ultimately nominates as Sessions' permanent replacement.

The news also came as the special counsel investigation into Russian meddling in the U.S. election in 2016, led by Robert Mueller, entered a critical — and possibly final — phase.

It's a tense moment for all the parties involved in the probe. Mueller has noticeably tightened his circle around Trump and his allies in recent weeks, as one high-profile member of the Trump team after another pled guilty to crimes and agreed to cooperate. Paul Manafort, Trump’s former campaign chairman, was the latest top Trump official to flip after reaching a cooperation deal with Mueller in early September — a decision that sent shockwaves through Washington.

Meanwhile, Trump made no secret of his displeasure with Sessions dating back to almost the start of his tenure, when the former Alabama senator recused himself from the Mueller probe citing previously undisclosed meetings with a Russian ambassador. Trump, who famously demands absolute loyalty from associates, spent the next 18 months complaining that Sessions had betrayed him by ceding control of the investigation to Rosenstein.

“Even my enemies say that ‘Jeff Sessions should have told you that he was going to recuse himself and then you wouldn’t have put him in.’ He took the job and then he said I’m going to recuse myself. I said, ‘what kind of a man is this?'” Trump told Fox in August. Later, he declared, "I don't have an attorney general."

On Twitter, Trump would routinely refer to Sessions as “weak” and “beleaguered,” and publicly referred to him around the White House as “mentally retarded” and a “dumb Southerner,” according to Bob Woodward's book, "Fear." Aides bought Sessions a bulletproof vest to celebrate the anniversary of his first year on the job, CNN reports.

Trump had been considering Whitaker for the role since at least early October, when the Washington Post reported that the two men had already met at least once to discuss succession plans. Whitaker was also previously floated as a potential replacement for Rosenstein, according to the New York Times.

Whitaker, who also served as the DOJ chief of staff during the George W. Bush administration, was appointed the U.S. Attorney for the Southern District of Iowa in 2004. He ran for the U.S. Senate in Iowa in 2014, but didn’t make it through the Republican primaries.

Trump confirmed Whitaker's new position in a tweet, saying in a follow up that he will name Sessions’ permanent replacement at a later date. “We thank Attorney General Jeff Sessions for his service, and wish him well!“ Trump wrote.

Sessions, a former senator from Alabama, landed his dream job as attorney general after serving as a surrogate for Trump on the campaign. Sessions saw an ideological ally in then-Candidate Trump, given his tough-on-crime rhetoric, hardline immigration views, and pro-law enforcement position.

His nomination was controversial, and during the confirmation process, Democrats highlighted the allegations of racism that once cost him a federal judgeship. His spotty record on civil rights, they argued, should have disqualified him. He was ultimately confirmed by a narrow margin, 47 to 52.

As Attorney General, Sessions moved swiftly to dismantle many Obama-era reforms in policing, criminal justice, and LGBTQ rights. Sessions positioned himself as an ally of police, who would restore the rule of law, and respect for law enforcement. He threw out an Obama-era policy that would phase out the use of private prisons, issued directives to bring back the war on drugs, and reversed a policy that gave civil rights protections to transgender Americans. He also championed Trump's harsh immigration policies that are still winding their way through federal courts across the country.

But Trump grew increasingly frustrated with Sessions when he made it clear that he wasn’t willing to be his personal lawyer, and made a habit of publicly lashing out at him. Sessions mostly stayed quiet in response to the president’s public criticism.

In March, Trump took to Twitter and chastised Sessions for pursuing an investigation into alleged surveillance abuses. "Why is A.G. Jeff Sessions asking the Inspector General to investigate potentially massive FISA abuse,” Trump wrote. “Will take forever, has no prosecutorial power and already late with reports on Comey etc. Isn't the I.G. an Obama guy? Why not use Justice Department lawyers? DISGRACEFUL!"

Sessions took the unusual move of responding Trump’s attack by putting out a statement.

"As long as I am the attorney general, I will continue to discharge my duties with integrity and honor,” Sessions said, “and this department will continue to do its work in a fair and impartial manner according to the law and Constitution.”

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