Mr Trump has been outwardly dissatisfied with Mr Sessions since the former senator relinquished oversight of special counsel Robert Mueller’s investigation into Russian election meddling last year.
He doubled down on this criticism in a string on tweets on Saturday morning, suggesting Mr Sessions had allowed politics to infiltrate the investigation into possible campaign collusion.
“Jeff Sessions said he wouldn’t allow politics to influence him only because he doesn’t understand what is happening underneath his command position,” Mr Trump tweeted.
“Highly conflicted Bob Mueller and his gang of 17 Angry Dems are having a field day as real corruption goes untouched. No Collusion!”
The president also quoted Republican Senator Lindsey Graham as saying that “every President deserves an Attorney General they have confidence in,” emphasising that cabinet positions are “not lifetime appointments”.
The tweets followed a week of attacks from the president, starting with a Fox and Friends interview in which he claimed Mr Sessions had failed to take control of the Justice Department, and said he only appointed the attorney general because of his early loyalty on the campaign trail.
Mr Sessions responded to the attacks with an uncharacteristically pointed statement, saying his department would not be “improperly influenced by political considerations”.
"I took control of the Department of Justice the day I was sworn in, which is why we have had unprecedented success at effectuating the President's agenda,” the attorney general said. "I demand the highest standards, and when they are not met, I take action."
The duelling statements indicate a deepening of the rift between the two men, which started when Mr Sessions recused himself the Mueller probe in March of 2017. He relinquished the role amid public outcry, after it was revealed he had failed to disclose his contacts with the Russian ambassador to the US.
Mr Trump has also taken issue with Mr Session's refusal to prosecute Hillary Clinton – the election rival the president repeatedly promised to "lock up" while on the campaign trail.
Mr Trump doubled down on this line of thinking on Saturday, claiming the FBI had ignored information in their investigation of Ms Clinton's private email server.
He appeared to be citing information from conservative website RealClear Investigations, which reported on Thursday that the agency had examined only 3,077 of the 694,000 emails discovered on a Clinton aide's laptop.
"I feel sure that we will soon be getting to the bottom of all of this corruption," he tweeted. "At some point I may have to get involved!"
Mr Trump has hinted repeatedly about wanting to replace his attorney general since last year, but has received little support from Republicans until this week.
Senator Chuck Grassley, the Judiciary Committee chairman, said on Thursday that he could make time for hearings to replace the attorney general after the end of the Supreme Court confirmation process – a possibility the senator has previously spurned.
Mr Graham, a sporadic critic of the president, told reporters that Mr Trump was “entitled to an attorney general he has faith in,” though he suggested waiting to replace Mr Sessions until after the November midterm elections.
“I think there will come a time, sooner rather than later, where it will be time to have a new face and a fresh voice at the Department of Justice,” the senator said.
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