Specifically, Mueller will explore the possibility that Trump obstructed justice.
In his testimony on June 8, Comey said Trump expressed hope the FBI investigation into former National Security Adviser Michael Flynn would conclude, but did not direct him to do so.
Investigators are seeking to determine if Trump tried to undermine the FBI’s ongoing probes of alleged Russian interference in the 2016 U.S. presidential election and collusion with Trump aides.
Mr Mueller was appointed as special counsel to investigate Moscow’s involvement in the presidential election previous year and possible collusion by Trump campaign associates with the Russians, but there has been no indication that Mr Mueller told the president to fire Mr Comey.
Earlier this week, the investigation led by Mueller appeared to move closer to Trump.
“They made up a phony collusion with the Russians story, found zero proof, so now they go for obstruction of justice on the phony story”, Trump said in a tweet shortly before 7 a.m.
Investigators have also been looking for any evidence of possible financial crimes by Trump associates, the daily said, quoting unnamed USA officials.
Accusations of obstruction arose last month when Trump fired FBI Director James Comey. The request specifically asked for “copies of all records of notes taken by or communications sent from FBI Director James Comey” regarding those interactions.
The White House is referring all questions regarding the Russian investigation to Trump’s outside attorney Marc Kasowitz.
“The interviews (with Rogers, Coats and Ledgett) suggest that Mueller sees the question of attempted obstruction of justice as more than just a “he said, he said” dispute between the President and the fired Federal Bureau of Investigation director, an official said”.
Top Democratic Senator Dianne Feinstein expressed concern that Trump may try to fire both Mueller and Rosenstein, warning “he’s in for a rude awakening” if he thinks he can shut down the investigation.
The Post report cites anonymous sources who were briefed on requests made by investigators.
Separately, the House committee said former Homeland Security Secretary Jeh Johnson would appear at a June 21 public hearing on the Russian Federation probe.
Peter Carr, a spokesman for Mueller, told AFP he now has “13 attorneys on board, with several more in the pipeline”.
Mark Corallo, a spokesman for Mr Trump’s personal lawyer, responded to the Washington Post’s report, saying: “The FBI leak of information regarding the president is outrageous, inexcusable and illegal”.
Deputy attorney general Rod Rosenstein, who appointed Mr Mueller last month, testified on Tuesday that he had seen no evidence of good cause to sack him.
“We may have our differences, but we do well in times like these to remember that everyone who serves in our nation’s capital is here because above all they love our country”, Trump said at the White House.