Jeff Sessions (photo by Gage Skidmore via Wikimedia Commons)

Jeff Sessions (photo by Gage Skidmore via Wikimedia Commons)

Attorney General Jeff Sessions, who frequently had been criticized publicly by President Trump for recusing himself in the Russia probe, submitted his resignation Wednesday.

In an undated letter, Sessions indicated Trump asked for the resignation.

Deputy Attorney General Rod Rosenstein is next in line. But Trump immediately tweeted that former U.S. attorney Matthew G. Whitaker, chief of staff to Sessions, will serve as acting attorney general.

“At your request, I am submitting my resignation,” Sessions wrote in a letter to Trump.

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

Saying he was “honored to serve,” Sessions wrote that his Justice Department “restored and upheld the rule of law – a glorious tradition that each of us has a responsibility to safeguard.”

Trump repeatedly had said over the last year that he regretted making Sessions attorney general. He would not have nominated him, he said, had he known Sessions would recuse himself from the Russia investigation.

“I don’t have an attorney general. It’s very sad,” Trump said in September.

Sessions explained when he removed himself from the Russia investigation in March 2017 that he didn’t want his role as an adviser to Trump during the 2016 campaign to create a conflict of interest.

Rosenstein, who normally would have become acting AG, is in charge of Robert Mueller’s special counsel investigation. The New York Times speculated that the bypassing of Rosenstein “might clear the way for Mr. Trump to fire Mr. Mueller.”

Senate Minority Leader Chuck Schumer was asked about Sessions’ resignation at a news conference Wednesday.

“Protecting Mueller and his investigation is paramount,” he said. “It would create a constitutional crisis if this were a prelude to ending or greatly limiting the Mueller investigation.”

Later, Schumer tweeted that the new acting AG, Whitaker, should recuse himself from the Russia 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 wrote.

Sessions was the first sitting senator to endorse Trump’s 2016 presidential campaign, becoming one of his closest national security advisers.

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