Former FBI Director James Comey said Thursday that former Attorney General Loretta Lynch asked him to downplay the investigation into Hillary Clinton's emails by not calling it an investigation.

"Probably the only other consideration that I guess I can talk about in an open setting is that at one point, the attorney general had directed me not to call it an investigation, but instead to call it a matter, which confused me and concerned me," he said when asked about the email investigation.

Comey said that request helped convince him that he had to put some distance between the Obama administration's Justice Department in order to wrap up that investigation.

"That was one of the bricks in the load that led me to conclude, 'I have to step away from the department if we're to close this case credibly,'" he said.

He also said President Bill Clinton's unplanned tarmac meeting with Lynch "ultimately" confirmed his decision to announce the result of his bureau's probe into Clinton's emails.

"That was the thing that capped it for me, that I had to do something separately to protect the credibility of the investigation, which meant both the FBI and the Justice Department," Comey said.

Comey was later asked more by Sen. James Lankford, D-Okla., about Lynch's request.

"Just call it a matter," Comey said he was told by Lynch.

When asked why he didn't push back against Lynch's request, Comey said it was because he decided, "This isn't a hill worth dying on, and so I just said, ‘Okay.' The press is going to completely ignore it – and that's what happened."

Still, he said Lynch's request "concerned me because that language tracked with how the campaign was talking about how the FBI was doing its work."

"I don't know whether it was intentional or not, but it gave the impression that the attorney general was trying to align how we describe our work" with how Clinton's campaign was talking about the FBI's investigation, he said. Lynch's requests gave him "a queasy feeling," Comey said.