Former U.S. Capitol Police Officer Harry Dunn, one of the officers most outspoken about the violence he witnessed during the Jan. 6, 2021, Capitol attack, announced Friday that he’s running for the U.S. House in Maryland’s 3rd Congressional District.

Dunn was one of the few officers who testified before the House Jan. 6 select committee about the racist slurs he endured during the Jan. 6 attack. He released a book last year, “Standing My Ground,” detailing his experience, and has received both the Congressional Gold Medal and Presidential Citizens Medal for serving during the insurrection.

Dunn, 40, announced his candidacy in a video Friday, on the eve of the third anniversary of the Capitol riot.

“On Jan. 6th, 2021, I did my duty as a police officer and as an American and defended our nation’s Capitol from violent insurrectionists,” he said in a statement. “Today, I’m running for Congress because the forces that spurred that violent attack are still at work and as a patriotic American, it is my duty to defend our democracy.”

Dunn, who stepped down late last year as a Capitol police officer after 15 years, is running in the crowded primary to succeed retiring Democratic Rep. John Sarbanes, whose district encompasses Howard County and parts of Anne Arundel and Carroll counties, all west of Baltimore. The winner of the primary is the favorite to clinch the heavily Democratic seat.

The former officer’s announcement video features a reenactment of Jan. 6 with a MAGA flag in the background. Dunn said he’s running in political opposition to Trump to prevent another Jan. 6-like attack from ever happening.

“We can’t ever let this happen again, and you’ve heard it from Trump himself: He is hellbent on finishing what he started this day,” Dunn says. “I believe every one of us has a role to play in this fight.”