Washington (CNN) An FBI special agent says he's turned in his badge so he can publicly voice his concerns over the politicization of the bureau by Republicans in Congress and the Trump administration.

"FBI agents are dogged people who do not care about the direction of political winds," former FBI special agent Josh Campbell, who was announced Monday as a CNN law enforcement analyst, wrote in a New York Times op-ed . "But to succeed in their work, they need public backing. Scorched-earth attacks from politicians with partisan goals now threaten that support, raising corrosive doubts about the integrity of the FBI that could last for generations."

The op-ed comes amid Republicans' increased scrutiny of the Justice Department and the FBI for their handling of the Russia investigation.

Campbell's piece was published Friday, the same day the Trump administration published an intelligence memo compiled by House Intelligence Committee Republicans that alleges FBI and Justice Department abuses of the Foreign Intelligence Surveillance Act. The memo accuses the FBI of improperly using information paid for in part by Hillary Clinton's campaign to obtain a FISA warrant for Trump campaign foreign policy adviser Carter Page.

Democrats have blasted the memo as a misleading document that omits key facts about the Page FISA application, accusing Republicans of using the memo to try to undermine special counsel Robert Mueller's probe.

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