Later, in a statement, McCain joked about social media's response to his questions. "I get the sense from Twitter that my line of questioning today went over people's heads," he said. "Maybe going forward I shouldn't stay up late watching the Diamondbacks night games."
What follows is a transcription of the exchange between McCain and Comey:
MCCAIN: In the case of Hillary Clinton, you made a statement that wasn't sufficient evidence to bring a suit against her although they'd been very careless in their behavior when you did reach a conclusion. In that case, that it was not necessary to pursue her. At the same time, in the case, Mr. Comey, who said that there was not enough information to make a conclusion. Tell me the difference between your conclusion as far as former Secretary Clinton is concerned and Mr. Trump.
COMEY: The Clinton investigation was a completed investigation that the FBI had been deeply involved in, so I had an opportunity to understand all the facts and apply those facts against the law as I understood them. This investigation was under way, still going when I was fired, so it's nowhere near in the same place, at least it wasn't when I was —
MCCAIN: But it's still ongoing.
COMEY: Correct. So far as I know. It was when I left.
MCCAIN: That investigation was going on, this investigation is going on. You reached separate conclusions.
COMEY: No, that one was done.
MCCAIN: That investigation of any involvement of Secretary Clinton or any of her associates is completed?
COMEY: Yes, as of July the Fifth, the FBI completed its investigative work and that's what I was announcing, what we had done and what we had found.
MCCAIN: Well, at least in the minds of this member, there's a whole lot of questions remaining about what went on, particularly considering the fact that as you mentioned, it's a, quote, big deal as to what went on during the campaign. So I'm glad you concluded that part of the investigation, but I — I think that the American people have a whole lot of questions out there, particularly since you just emphasized the role that Russia played. And obviously she was a candidate for president at the time. So she was clearly involved in this whole situation where fake news, as you just described it, big deal took place. You're going to have to help me out here. In other words, the investigation of anything that former Secretary Clinton had to do with the campaign is over and we don't have to worry about it anymore?
COMEY: With respect to Secretary — I'm a little confused, Senator. With respect to Secretary Clinton, we investigated a criminal investigation in connection with her use of a personal e-mail server.
MCCAIN: I understand.
COMEY: And that's the investigation I announced the conclusion of on July 5.
MCCAIN: But at the same time you made the announcement there would be no charges brought against then-Secretary Clinton for any activities involved in the Russia involvement, engagement in our election. I don't quite understand how you can be done with that but not complete – done with the whole investigation of their attempt to affect the outcome of our election.
COMEY: No. I'm sorry, we're not — at least when I left, when I was fired on May the ninth, there was an open active investigation to understand the Russian efforts and whether any Americans worked with them.
MCCAIN: But you reached the conclusion that there was no reason to bring charges against Secretary Clinton. So you reached a conclusion in the case of Mr. Comey, President Comey — excuse me, the case of Mr. Trump, you have an ongoing investigation. So you've got one candidate who you're done with and another candidate that you have a long way to go. Is that correct?
COMEY: I don't know how far the FBI has to go, but yes. The Clinton e-mail investigation was completed. The investigation of Russia's efforts in connection with the election and whether there was any coordination, and if so with whom between Russia and the campaign was ongoing when I left.
MCCAIN: You just made it clear in what you said, this is a, quote, big deal, unquote. I think it's hard to reconcile in one case you reach a complete conclusion and the other side you have not. And in fact, obviously there's a lot more there as we know, as you called it a, quote, big deal. She's one of the candidates. But in her case you say there will be no charges and in the case of President Trump, the investigation continues. What has been brought out in this hearing is more and more emphasis on the Russian engagement and involvement in this campaign. How serious do you think this was?
COMEY: Very serious. I want to say something to be clear. We have not announced and there was no predication to announce an investigation of whether the Russians may have coordinated with Secretary Clinton's campaign. Secretary Clinton's campaign —
MCCAIN: No, but they not have been involved with the campaign, they were involved with the entire presidential campaign obviously.
COMEY: Of course, yes sir. And that is an investigation that began last summer. So far as I'm aware, continues.
MCCAIN: So both President Trump and former candidate Clinton are both involved in the investigation, yet one of them you said there's going to be no charges. In the other one, the investigation continues. Well, I think there's a double standard there to tell you the truth. Then when the president said to you, you talked about the April 11 phone call, he said, quote, because I've been very loyal to you, very loyal. We had that thing, you know. Did that arouse your curiosity as to what, quote, that thing was?
MCCAIN: Why didn't you ask him?
COMEY: It didn't seem to me to be important for the conversation we were having to understand it. I took it to be some – an effort to communicate to me that there is a relationship between us where I've been good to you, you should be good to me.
MCCAIN: Yeah, but I'd think it would intensely arouse my curiosity if the president of the United States said we had that "thing," you know. I'd like to know what the hell that thing is, particularly if I'm the director of the FBI.
COMEY: I get that, Senator. Honestly, I'll tell you what, this is speculation. But what I concluded at the time was in his memory he was searching back to our encounter at the dinner and was preparing himself to say I offered loyalty to you, you promised loyalty to me and all of a sudden his memory showed him that did not happen and I think he pulled up short. That's just a guess, but I've had a lot of conversations with humans over the years —
MCCAIN: I think I'd have some curiosity if it had been about me, to be honest with you. So are you aware of anything that would lead you to believe that the president, or the members of the administration, or members of the campaign could potentially be used to coerce or blackmail the administration?
COMEY: That's a subject for investigations, not something I can comment on sitting here.
MCCAIN: But you reached that conclusion as far as Secretary Clinton was concerned, but you're not reaching a conclusion as far as this administration is concerned. Are you aware of anything that would lead you to believe that information exists that could coerce members of the administration or blackmail the administration?
COMEY: That's not a question I can answer, Senator.
SEN. RICHARD BURR: The senator's time has expired.
MCCAIN: Thank you.