Washington (CNN) A former FBI agent who turned in his badge last week because of "relentless" attacks and what he sees as the GOP's politicization of the bureau says that the situation is having a "cascading effect" on the rank-and-file staff within the organization.

"What we need to be concerned about -- and I hope that our leaders are concerned about -- is a cascading effect on the FBI agent on the street, the intelligence analyst, professional staff employee, who gets up every single day working to defend the Constitution and protect the American people. Josh Campbell, who is now a CNN law enforcement analyst, told CNN's "New Day" Monday morning.

Campbell was reiterating a central point in his New York Times op-ed published on Friday, in which he explained why he was leaving the bureau. The former special agent's decision to leave the organization comes amid Republicans' increased scrutiny of the Justice Department and the FBI for their handling of the Russia investigation.

"The only reason people will talk to us is if they trust us," Campbell told "New Day." "And what I'm afraid of is that ... this corrosive doubt about the agency that's been able to seep into the national discussion because of politics, is something that's going to negatively impact our ability to do our job."