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Jeff Sessions has resigned as attorney general effective immediately after being asked to do so by President Trump, sources told ABC News.

"At your request, I am submitting my resignation," Sessions wrote in an undated letter to the president.

The president tweeted that Matthew Whitaker, chief of staff to Sessions, will become the acting attorney general, reports Fox News. "We are pleased to announce that Matthew G. Whitaker, Chief of Staff to Attorney General Jeff Sessions at the Department of Justice, will become our new Acting Attorney General of the United States. He will serve our Country well," he said.

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