Multiple news outlets are reporting that Attorney General Jeff Sessions offered his resignation to the White House. Trump has been angry with him ever since he offered to recuse himself from the #TrumpRussia investigation, leading one to think Trump hoped there would be someone else in place to help cover up the campaign collusion with the Russian government.
Sessions said he would recuse himself from all things regarding that investigation when it was found out that he lied during his Senate confirmation hearings about meeting with Russian officials (he did so twice) during his time as a Trump campaign surrogate. Incidentally, it was recently discovered that there was a third, unreported meeting.
Due to already high tensions between the two since Sessions recused himself, it is now being said that Trump is also angry because of the bad press the Attorney General has been getting because of the prior Russian connections. Frustration with the Justice Department not being able to do anything about Trump’s proposed travel ban being stopped by the court system has also played a part in the animosity.