On CNN, New York Times reporter Maggie Haberman says Trump wanted to prosecute Clinton for the far right wing's fake "Uranium One" story, and Comey for "leaking". "This is what he's been so vocal about now and speaking out".
Trump's former lawyer, John Dowd, urged Deputy Attorney General Rod Rosenstein in a memo previous year to investigate Comey and his handling of the Clinton email investigation.
Trump has repeatedly and publicly called on the Justice Department to investigate Clinton, and he has tweeted his dismay over what he saw as former Attorney General Jeff Sessions' reluctance to go after Clinton.
In January, CNN reported that the Arkansas attorney and FBI were investigating possible corruption within the Clinton Foundation.More news: Cowboys' DeMarcus Lawrence: We're One of NFL's Best Defenses
They were also looking into if any tax-exempt funds were misused.
Presidents typically go out of their way to avoid any appearance of exerting influence over Justice Department investigations.
"Mr. McGahn will not comment on his legal advice to the president", his lawyer, William Burck, told the Times.More news: Charles Howell III ends long wait for PGA Tour win
McGahn wrote a memo to dissuade Trump, noting that the potential consequences for such an action could include impeachment, according to the report.
Mr McGahn left the White House in October amid frictions with the President.
Trump fired Comey in May 2017 over his handling of the investigation into Hillary Clinton's use of private email server and email accounts for official business during her tenure as secretary of state from 2009 to 2013.
"I look at what's happening with the Justice Department", he said in a 2017 radio interview.More news: Dead whale had 115 plastic cups and 2 flip-flops in its stomach