PORTLAND — The man who was at the helm of Oregon’s highest-profile terrorism arrest has announced his candidacy for state attorney general, adding to a growing field of Democrats running for the seat.

Dwight Holton, who served in an interim capacity for 20 months as Oregon’s U.S. attorney, was law enforcement’s public face during the arrest and arraignment of a Somali-American teen charged with attempting to detonate a weapon of mass destruction at a 2010 Christmas tree-lighting ceremony.

In an email seeking support from Oregon attorney associations, Holton pitched himself as an effective leader who got results in his short stint at the helm of the U.S. Attorney’s Office.

“Throughout my career I have held one central principle: be on the side of the people,” Holton wrote in the email sent Wednesday morning. “I am asking for your support because I believe that now more than ever, we need an Attorney General with those values and a track record of leadership, experience and results.”

The letter also includes references to support of environmental causes and education — two powerful lobbies in Salem. A website launched Wednesday highlights his focus on reducing prescription drug abuse, focusing on civil rights and fighting white-collar crime.

The son of former Virginia governor Abner Linwood Holton, Holton graduated from the University of Virginia’s law school in 1996. As a young assistant U.S. attorney in New York, Holton prosecuted murder, terrorism and organized crime cases. He joined the U.S. Attorney’s Office in Oregon in 2004.

The incumbent, Oregon Attorney General John Kroger, has said he will not run for re-election, citing an unspecified health condition. No Republican has announced plans to run. The party has had difficulty getting attorney general candidates and four years ago actually nominated Kroger.

Holton’s top competition is expected to be fellow Democrat Ellen Rosenblum, a retired Oregon Court of Appeals judge with experience as a federal prosecutor. Since announcing her intention to run for office on Jan. 4, Rosenblum has collected more than $15,000 in contributions.

Rosenblum said Wednesday that her experience in the state court system, both as an attorney and a judge, gives her experience Holton doesn’t have.

“Mr. Holton has never been a lawyer in the state courts of Oregon,” Rosenblum said. “That’s a whole lot different system. He just became a member of the bar two years ago.”