Comey said what "capped" his decision to make his public remarks about the conclusion was a publicly reported meeting
by Lynch and former President Bill Clinton as their planes were on the same tarmac. He said he decided he had to "protect the credibility of the investigation."
That was public knowledge and drew criticism at the time, but Comey also revealed that Lynch had previously given him instructions on the investigation into the use of a private server by former Secretary of State Hillary Clinton -- which "concerned" him.
"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," Comey said. "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 later explained that it felt "silly" to not acknowledge the investigation publicly as both presidential campaigns were speaking publicly about it -- but said the Clinton campaign was using "euphemisms" for it, including a "matter."
He said he asked the attorney general, in the likelihood they would both have to testify, if he could confirm there was an investigation.
"I wanted to know, was she going to authorize us to confirm we had an investigation, and she said, 'Yes, but don't call it that, call it a matter,'" Comey said. "And I said, 'Why would I do that?' And she said, 'Just call it a matter.'"
Comey said he didn't push back.
"I said (to myself), 'This isn't a hill worth dying on, OK."
But he said the matter gave him a "queasy feeling."
Comey was testifying Thursday before the Senate intelligence committee on the government's investigation into Russian meddling in the US election and his firing by President Donald Trump.
But he also faced questions about his fateful decision last summer to make public statements on the results of the FBI's investigation into the Clinton server, which were cited by Trump and Justice officials in the first explanation of Comey's firing. Trump later said "this Russia thing"
was a factor in his decision to fire Comey.
Comey also called other explanations of his decision to make his conclusions on Clinton public "nonsense" , referencing press reports that a fabricated document -- which he knew to be fake
at the time -- influenced his thinking.
Lynch did not respond to a request for comment. A former spokeswoman for Lynch vented her anger on Twitter.
"The irony of him throwing Lynch under the bus but claiming victim with Trump is THICK. He needs to be called on this. #ComeyHearing," Melanie R. Newman tweeted