(CNN)FBI Director Christopher Wray underscored the importance of protecting the identity of human sources in testimony Wednesday amid an ongoing battle with House Intelligence Committee Chairman Devin Nunes and other House Republicans over the disclosure of a document the Justice Department says would endanger a source.
FBI director defends agency amid scrutiny from House Republicans
"The day that we can't protect human sources is the day the American people start becoming less safe," Wray told members of the Senate Appropriations Committee. "Human sources in particular who put themselves at great risk to work with us and with our foreign partners have to be able to trust that we're going to protect their identities and in many cases their lives and the lives of their families."
Wray said he respected Congress' oversight duties and "we welcome the tough questions given our responsibilities" but defended the pace of the bureau's document production, as the FBI and Justice Department have faced subpoenas and criticism from House Republicans.
In March, Wray said he doubled the number of staff who were reviewing documents requested as part of one Hill probe.
"We actually have been dealing with quite a number of requests, some of them almost unprecedented in their volume from a number of different committees," Wray said Wednesday. "We're chugging away, making progress."
"Every week we're cranking out documents and people are coming over to spaces that we have set aside from the Hill to review documents. So it's an ongoing process, thousands of documents being released," he said.
Sen. Patrick Leahy, a Vermont Democrat, called suggestions by Nunes that Wray should be impeached over the document spat "beyond balderdash" and "one of the dumbest statements I've heard any member of Congress in either party ever say."
Asked by Leahy if he stood by his past testimony that the Russia investigation is not a witch hunt -- as President Donald Trump has repeatedly called it -- Wray said "yes."
Wray defended the integrity of bureau, but declined to directly address criticism leveled at the FBI by President Trump at several points during the hearing.
"We have seen, I think tragically, a series of public statements by President Trump suggesting that the investigation into Russian interference in the 2016 election is 'a witch hunt'. He literally said last month 'you look at the corruption at the top of the FBI, it's a disgrace,'" Democratic Sen. Chris Coons said.
The senator then brought up a recent poll that showed a majority of Republicans said the FBI and the Justice Department are framing the president.
Wray responded by saying, "While I recognize there are a lot of opinions out there, we don't focus on polls, and surveys and studies. We focus on, as I said, the opinions of the people who know us through our work. And what I find when I go out and talk to people in the field out on the front lines -- our partners, the judges, the prosecutors, the victims -- the feedback I get, uniformly, is positive and supportive."
Leahy also brought up Trump's criticism of the FBI, and expressed concern over what he described as "the relentless, politicized attacks on our nation's law enforcement" by the administration. The Democratic senator then asked Wray if he believes "the men and women of the FBI working on the Russia investigation are driven by anything other than a duty to the rule of law and to ensuring that anyone who attacked our democracy in 2016 is held accountable?"
Wray did not weigh in on the President's criticism, sticking to praise for FBI agents instead.
"The agents that I have worked with since being on the job have inspired me every day in terms of their professionalism, their integrity, their courage and their commitment to doing the right thing in the right way," he said.