After admitting last week that "protocol was not followed" when at least two individuals called the FBI's anonymous tip line to warn that Nikolas Cruz, the 19-year-old suspected of murdering 17 of his former classmates, the No. 2 FBI official said Thursday that he had visited the FBI's call center this week as part of his review of why the tip wasn't followed.

He also addressed, in the most detail yet, the mounting criticisms facing the bureau, according to the Washington Post.

The remarks followed NRA spokeswoman Dana Loesch's assertion that the FBI was primarily to blame for not preventing the shooting.

Shortly before Bowdich spoke Thursday, NRA chief executive Wayne LaPierre, who was speaking at the same event, said the FBI's leaders had gone "rogue."

Acting deputy director David Bowdich said he believes the biggest threat to the FBI is "losing the faith of the American people"

"Look, I don’t want to get into who says what, but I do want to project out to the public, is when I look through the prism of risk for our organization, I find the number one risk for our organization is losing the faith and confidence of the American people. Number one," Bowdich said when asked about the criticism from the NRA and others.

FBI Director Christopher Wray - who was appointed by Trump - has come under fire, with several prominent Republicans, including Florida Gov. Rick Scott, calling for him to resign. President Trump has said the bureau’s handling of the matter was “not acceptable.”

Still, while Bowdich provided some details about his visit to the FBI call center, he offered no new insight into why or how the tip wasn't followed up on. The FBI is actively investigating why the tip wasn't passed on to its Miami field office.

Bowdich said Thursday that he had visited the call center Monday with a team and sat in on some calls. He called the center “a professional operation” but added: “Now let me be clear that there was a mistake made. We know that. But it is our job to make sure that we do everything in our power to ensure that does not happen again.” Bowdich did not directly address a question about why the tip on Cruz was not passed to agents in the field, though he hinted that those in the call center might have made a judgment error. "People make judgments out on the streets every day. Every now and then, those judgments may not have been the best judgment based on the information they had at the time," Bowdich said.

Last year, the FBI received about 765,000 calls, in addition to about 750,000 Internet tips, and 9 out of 10 did not produce leads that could be followed. He said the bureau was going back through its "holdings" to make sure there aren't any other similar tips that have slipped through the cracks.

Wray has held on so far, and speculation is mounting that he might stay on to supervise the internal probe into why, exactly, these tips weren't followed up on.