During a highly-anticipated Senate Intelligence Committee hearing, the New Mexico Democrat confronted Sessions about his refusal to reveal non-classified conversations with the president after Sessions dodged a question about whether Trump expressed dissatisfaction over Sessions' recusal from the investigation into Russia's interference in the 2016 election.
In another exchange with lawmakers, Sessions disputed Comey's testimony about a key discussion the two of them had in February, after the president met with Comey alone and privately suggested the Federal Bureau of Investigation drop its probe of former national security adviser Michael Flynn.
Sessions also told the committee that Comey did not tell him that President Trump brought up Michael Flynn when they were alone in the Oval Office. "He - I knew him before that, and I have confidence in Mr. Mueller". He told Sessions: "You're impeding this investigation".
However, Sessions could invoke executive privilege during his testimony depending on "the scope of the questions", the White House suggested on Monday.
In a combative and emotional Senate hearing, Sessions beseeched his former Senate colleagues to believe him when he said he did not hold a meeting with Russian ambassador Sergey Kislyak at a speech by then-candidate Donald Trump at the Mayflower hotel past year.
Ahead of the hearing there had been suggestions that Sessions might have had a third, unreported, encounter with Kislyak, at the Mayflower Hotel in April 2016, where candidate Trump was giving his first major foreign policy speech.
"Well, some of that leaked out of the committee that he said in closed session", Sessions said.
"The Attorney General has requested that this hearing be public", Justice Department spokeswoman Sarah Isgur Flores said in a statement.
And would Sessions and Rosenstein risk being fired themselves and refuse to fire Mueller?
And then an ally of President Donald Trump suggested the president is thinking about firing the special counsel investigating the Russian Federation issue. "And I'm trying to give my best recusal answer in committees I've appeared before, and really people are suggesting through innuendo that I have not been honest about matters, and I'm trying to be honest".
Rosenstein repeatedly conveyed his support for Mueller's role at a Senate hearing, held the morning after a close friend of President Donald Trump was quoted in a television interview as saying he was considering dismissing Mueller. "I have confidence in Mr. Mueller".
Some of the questions likely to be posed to Sessions will focus on his meetings with Russian Ambassador Sergey Kislyak during the campaign.
He was asked about the event several times, and said at one point, "If any brief interaction occurred in passing with the Russian ambassador during that reception, I do not remember it".
Schiff says that if Trump fires Mueller, Congress might name its own independent counsel to investigate the case. The Justice Department has denied that, saying Sessions stressed to Comey the need to be careful about following appropriate policies.
Democrats were unhappy with Sessions declining to testify about his discussions with Trump.
Sessions criticized Comey's handling of the Hillary Clinton email investigation, which the White House had initially cited as the ostensible reason for his firing.
Last week, Comey raised additional questions about Sessions' involvement, saying the FBI knew of reasons why it would be problematic for the attorney general to stay involved in the Russian Federation investigation well before Sessions recused himself in March. He asserted that "I am protecting the right of the president to assert if it he chooses and there may be other privileges that may apply". But the Russian Federation investigation continues to cast a shadow over his tenure.