If Trump fires the attorney general or forces him out, he will almost certainly do himself more damage than good. First, he would antagonize Sessions's friends in Congress — which ultimately could hold Trump's fate in its hands. Second, he would make himself look as though he is doing everything he can to foil the investigation, which suggests guilt. He may have real trouble finding any respected person to take the job. Finally, he would give Sessions reason to get even by going public with anything damaging he knows about the president.