In an interview with NPR's Morning Edition, fired FBI Director James Comey defended his controversial decisions during the 2016 campaign and asserted that the reputation of his agency — which operates under near daily siege from the president and his allies — "would be worse today had we not picked the least bad alternatives."

"I saw this as a 500-year flood, and so where is the manual? What do I do?" he said.

Comey responded to a new round of personal attacks from the White House by underscoring how President Trump has made once out-of-bounds behavior seem unremarkable. Trump suggested over the weekend on Twitter that the former FBI director should face jail time.

"The president of the United States just said that a private citizen should be jailed," Comey said. "And I think the reaction of most of us was, 'Meh, it's another one of those things.' This is not normal. This is not OK. There is a danger that we will become numb to it and we will stop noticing the threats to our norms, the threats to the rule of law and the threats, most of all, to the truth."

In his new book, A Higher Loyalty, Comey describes Trump as unfit for the nation's highest office, but stops short of concluding there's a strong case against the president for obstructing justice. There's some evidence of it, though, he said, citing his surprise dismissal in May 2017 after the president asked him to go easy on an investigation of former national security adviser Michael Flynn.

Current and former law enforcement experts have suggested writing a book and doing a blitz of media appearances could complicate any possible prosecution or impeachment proceeding in the future. But Comey deflected that idea in the NPR interview.

He said, "Normally, you don't want your witnesses out talking if they're going to have to testify later. ... The advantage in my circumstance is that my testimony is locked down. I testified in front of Congress extensively; I wrote memos, I wrote written testimony. And so long as I continue to tell the truth, and don't start making stuff up that's inconsistent with that testimony, I don't see an issue. Again, I don't know whether there's going to be a future proceeding where I'll be needed, but if there is, I think the prosecutors'll be OK with me."

Comey's book delivers tough words for the current Justice Department leaders, Attorney General Jeff Sessions and Deputy Attorney General Rod Rosenstein. Sessions is described as "overwhelmed and overmatched by the job." And Comey has said that Rosenstein acted "dishonorably" by allegedly helping advance a pretext for Comey's dismissal last year. Recently, the White House declined to say whether either man had job security.

Comey said, "With respect to the deputy attorney general, I think it is very important that he stay because I do think he has conducted himself honorably with respect to his appointment of a special counsel and his assertion of that special counsel's work to the rule of law. And so I really do think it would be an attack on the rule of law for him to be fired or for the special counsel to be fired."

Comey addressed another recent personnel move — the dismissal of former FBI Deputy Director Andrew McCabe only hours before his full law enforcement pension vested. McCabe was let go after an inspector general found he had demonstrated a "lack of candor" to investigators probing FBI contacts with The Wall Street Journal during an investigation into the Clinton Foundation in 2016. Comey expressed confidence in the inspector general, but said the president had "stained" the process.

"The problem with this whole situation is the president stained those institutions — the entire Department of Justice and the inspector general — by doing something wildly inappropriate, which is calling for Andy McCabe's head. ... That called into question the entire process, so even if the process was sound, and I've no doubt it was sound ... there's corrosive doubt about whether it's a political fix to get Andy McCabe somehow. And that's a wound that was inflicted by the president's actions on the Department of Justice."

Comey also responded to critics who questioned why he included negative personal descriptions about the size of the president's hands, his elaborate hairstyle and the length of his tie.

"I'm not making fun of the president," Comey said, "I'm trying to be an author, which I've never been before in my life. While I'm typing, I can hear my editor's voice ringing in my head: 'Bring the reader with you, show them inside your head.' ... And by the way, not that this matters, but I found his hands to be above average in size. I'm not making fun of the man, I'm trying to tell the reader what's in my head."

While his decisions about the Hillary Clinton email investigation and the probe of Russian interference in the election may have marked an end to his long run in law enforcement, Comey maintained he would not do things much differently if he had a chance. Asked about mistakes, he cited careless language in a speech that infuriated the Polish government and the "thoughtless way" he entered the debate about encryption and the technology industry.

As for his future, Comey ruled out a run for political office — an idea his friends have floated, and which he may have teased by posting a photo on social media last year, standing on a road in Iowa.

"Never, I will never run for office, not even a close call," Comey said.

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