Concealing the Clinton email probe status would have been 'catastrophic,' Comey says

"So as between bad and catastrophic, no matter where the polls are, you're going to have to always choose bad, and know you're going to get hammered for it, but know you had two choices and you chose the least bad," Comey said at a CNN town hall.

As FBI director, Comey made the decision shortly before the election to tell Congress the bureau was re-opening its probe into the Democratic nominee's email practices as secretary of state, and on Wednesday acknowledged the criticism he continues to hear on that choice.

"It appears to a lot of folks, 'you treated the Hillary Clinton case different than the Russia case,'" Comey said.

Comey said it is "important to realize" that the Clinton investigation began via a public referral to the FBI, whereas the investigation into potential coordination between President Donald Trump's associates began as a small counterintelligence probe that did not include Trump.

"Candidate Trump was not the subject of an FBI investigation," he said.

Comey acknowledged in his book that he could not be sure his belief that Clinton would win the 2016 election played into his decisions during the campaign. On Wednesday, he said that he would have made the same call on the email announcement regardless of the polls.

"The air I was breathing was, Hillary Clinton is going to be elected, but, this is something I don't think I make clear in the book, the answer would be the same," Comey said. "As between those two options, no matter where the polls stood, you can't conceal a material, huge change in facts from the American people when you've told them the opposite."