Katie Arrington has resigned her post at DoD and sources say she is telling colleagues that she intends to challenge Rep. Nancy Mace, R-S.C., in a South Carolina Republican primary this year. (Air Force Staff Sgt. Brittany A. Chase/DoD)

Katie Arrington, the cybersecurity official hired by the Trump administration to stand up the Cybersecurity Maturity Model Certification program at the Department of Defense and who was placed on administrative leave last year following accusations by the DoD and NSA that she disclosed classified information, has resigned from her post.

In her letter obtained by SC Media addressed to Assistant Secretary Deborah Rosenblum and Deputy Assistant Secretary of Defense Jesse Salazar, Arrington reiterated claims made in a lawsuit she filed against the federal government last year that DoD and NSA officials have not substantiated their original charge that a security violation took place. She accused the DoD and Biden administration of taking action because of “ridiculous internal to-DoD power grabs,” her political beliefs and her intentions to complain about a hostile work environment.

"The suspension of my clearance was, in my perception, a politically influenced action driven to silence me because I was in the process of filing a Hostile Work Environment claim" against Deputy Assistant Secretary of Defense Jesse Salazar, Arrington wrote. Salazar took over management of the CMMC after she was placed on leave.

The move clears the way for the now-former DoD official to resume her political career. Sources told SC Media that Arrington, who ran for Congress in 2018 as a Republican in South Carolina's 1st District, is telling others that she plans to announce this week she will run again for the same seat. That seat is currently held by Republican Nancy Mace, who has drawn the ire of former Republican President Donald Trump for perceived acts of disloyalty and could face a primary challenge.

Arrington’s lawyer Mark Zaid, declined last week to comment on whether Arrington intended to run, but said in a statement Monday that his client is currently "contemplating her next career steps." One day later, Arrington announced her run and repeated false and debunked claims spread by former President Donald Trump that electoral fraud caused his defeat in the 2020 Presidential election. (This reporter covered election security for three years leading up to the 2020 elections and these claims are nonsense. Dozens of court challenges -- including many in front of judges nominated by Trump himself -- failed to identify or overturn a single fraudulent vote across the country.)

Katie Arrington's resignation letter.

In the past two weeks, the federal government moved to settle Arrington’s lawsuit, though the underlying claim that she disclosed unauthorized classified information has not been resolved and her clearance remains suspended. Days later, DoD officials sent out a memo eliminating Arrington’s position and formally shifted oversight of CMMC and other responsibilities to the chief information officer.

Arrington, a businesswoman and Republican political candidate who also worked in the defense contracting industry, was initially appointed by the Trump administration as chief information security officer for acquisition in the Office of the Under Secretary of Defense for Acquisition and Sustainment. She was placed on administrative leave in May 2021, four months after the Biden administration took over.

Arrington also said her name had been disparaged within government and defense contracting circles over the past year as the accusations hung over her head, and despite being given assurances that she would be interviewed, there is “absolutely no evidence any substantive security investigation was conducted by any federal agency.” According to court documents, the Air Force Office of Special Investigations reviewed the incident and concluded a counterintelligence investigation was not warranted.