AUDIE CORNISH, HOST:

Senators questioned the Justice Department inspector general for hours today about the FBI's investigation of the 2016 Trump campaign and its possible connections to Russia. Michael Horowitz stuck to the findings in his 400-plus-page report. He said the FBI had sufficient grounds to launch its probe but stumbled through error after error in surveilling a former Trump aide. No one involved in the investigation, he said, was vindicated. Let's go now to a senator who questioned Horowitz, Democrat Chris Coons of Delaware.

Welcome to the program.

CHRIS COONS: Thanks, Audie.

CORNISH: Can you say with confidence that the FBI did not let political bias creep into its probe?

COONS: What was important, I think, about the IG's report today and his testimony in front of the Judiciary Committee was that he debunked the conspiracy theories that have long been pushed by President Trump, his attorney general and his supporters, that the whole Mueller investigation was an unwarranted, unjustified hoax, that it was a witch hunt. Inspector General Horowitz stood by his report's core findings that Russia was engaged in an unprecedented attack on our election and the FBI was without bias and properly and well-founded in launching an investigation into possible ties between the Trump campaign and Russian interference.

CORNISH: At the same time, this is the cream of the crop at the FBI, right? And yet they made 17 errors on this extremely sensitive investigation. Is that cause for alarm?

COONS: Well, we shouldn't minimize the errors in the FISA application that were detailed by Inspector General Horowitz. And I commend the FBI director, Chris Wray, for acting promptly to implement the IG's recommendations. But it's important to put these errors in context. Carter Page, who was the subject of that FISA application, wasn't indicted in the Russia investigation. He was the only Trump campaign official targeted with a FISA warrant. And in the end of the investigation, President Trump's campaign manager, his national security adviser and his personal attorney were all either convicted or pled guilty. And nothing in this report about those irregularities with regards to the FISA warrant disturbs those convictions or the total of 37 indictments and convictions that were the outcome of the Mueller report.

CORNISH: What's your response to, say, Senator Lindsey Graham raising this idea that, look; if you have an FBI who's this cavalier about secret courts and civil liberties, that this is something the average citizen should be worried about as well?

COONS: Well, as I said in my questioning of the inspector general, we shouldn't overlook these irregularities, and we should be making a good faith, bipartisan effort at re-examining the FISA warrant process. If that had been the real focus of this hearing today, we would have spent most of our time talking about the recommendations that the IG made in his report for how to improve that FISA process. The vast majority of today's hearing, in my view, was mostly political theater. It was reciting at great length a few exchanges between two particular FBI-related investigators. The inspector general found that there were messages or texts exchanged that were pro-Trump and that were anti-Trump but that none of that influenced the launching of this investigation into the Trump campaign or its ultimate conclusions.

CORNISH: On that point, the report found that according to the FBI's own rules, the agency did have adequate basis to start its investigation. At the same time, we heard people raising issues today about whether the rules should be different or more stringent. I mean, should there be a higher bar for such a sensitive investigation?

COONS: I think there should be. And the inspector general laid out a number of suggestions for how the internal review and approval process for an investigation of this extremely high sensitivity should be carried out. So it's my hope that those of us who are concerned about holding federal law enforcement accountable but also supporting the men and women of the FBI will work together to make sure that those recommendations that have, by the way, been welcomed by FBI director Ray will be thoroughly implemented.

CORNISH: The attorney general has, of course, ordered a separate, broader report into the investigation, this one by U.S. attorney John Durham. He's already said he doesn't agree with some of the inspector general's conclusions. So do you think his report will, I don't know, carry more weight?

COONS: I frankly think it will carry less weight because the inspector general, who's now served for many years across several administrations, is someone who has been praised for his independence, his professionalism, his effectiveness previously by the attorney general himself. And I think you can't have a more thorough investigation. They interviewed more than 100 witnesses. They had 170 interviews. They reviewed a million pages of documents. This was a thorough and searching investigation. I conclude that the attorney general just dislikes the conclusion that the inspector general reached and is trying to craft an investigation to reach a different result.

CORNISH: Chris Coons is a Democratic senator from Delaware. He sits on the Judiciary Committee.

Thank you for your time.

COONS: Thank you, Audie. Transcript provided by NPR, Copyright NPR.