United States Attorney General Jeff Sessions has resigned. Sessions announced his resignation in a letter to President Donald Trump on Wednesday. He wrote, “At your request, I am submitting my resignation.” Trump announced on Twitter that Session’s chief of staff, Matthew Whitaker, a former United States attorney from Iowa will become acting attorney general. Trump thanked Sessions for his service and said “a permanent replacement will be nominated at a later date.” The resignation brings to an end a difficult relationship between the two men. Trump strongly criticized Sessions’ decision to step aside from the investigation into Russian interference in the 2016 presidential election. Sessions did so after it was reported that he met with Russian officials before the election. Sessions had also served on Trump’s election campaign team. Sessions’ admission angered Trump who said he never would have nominated the former Alabama senator if he knew he would have stepped aside.