The Justice Department is reportedly blocking Senate investigators  from  speaking with FBI officials who may provide first-hand testimony  about  Donald Trump's firing of ex-FBI chief James Comey. It is the latest  sign that Special Counsel Robert Mueller could be  investigating the  sacking as part of his Russia-related probe.

President Trump told the White House counsel in the spring that he wanted to order the Justice Department to prosecute two of his political adversaries: his 2016 challenger, Hillary Clinton, and the former F.B.I. director James B. Comey, according to two people familiar with the conversation. The lawyer, Donald F. McGahn II, rebuffed the president, saying that he had no authority to order a prosecution.

During a news briefing on Wednesday, Press Secretary Sarah Huckabee Sanders made the administration’s case for prosecuting former FBI Director James Comey from the White House podium. In making the comments, Sanders is disregarding what was previously an important ethical standard — that the Justice Department has prosecutorial independence. The idea is that the Justice Department should decide who to prosecute based on a unbiased application of the law, not political pressure from the White House. This is something that neither Sanders or her boss seem to value.

President Trump and his advisers are privately discussing the possibility of replacing Attorney General Jeff Sessions, and some confidants are floating prospects who could take his place were he to resign or be fired, according to people familiar with the talks.

President Trump put fresh pressure on the second-highest-ranking  official at the Justice Department on Friday, raising concerns among the  president’s critics that Rod J. Rosenstein could be in danger of being fired, while others argued that if he stays he should recuse himself  from his role overseeing the special-counsel probe that has engulfed the White House. “I am being investigated for firing the FBI Director by the man who told me to fire the FBI Director! Witch Hunt,” the president said on Twitter.