By Laura Jarrett, CNN

(CNN) -- President Donald Trump on Wednesday fired Attorney General Jeff Sessions.

"At your request I am submitting my resignation," Sessions wrote in a letter to White House chief of staff John Kelly.

Matthew Whitaker will take over as acting attorney general, the President said.

Whitaker is expected to take charge of the the Russia investigation and special counsel Robert Mueller from Deputy Attorney General Rod Rosenstein.

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

Trump did not answer a direct question about Sessions during his news conference Wednesday, saying that on the whole he is "extremely" satisfied with his Cabinet.