Adam Kline, an unabashed liberal firebrand and civil-liberties advocate who has represented South Seattle in the state Senate for 17 years, announced Thursday he will not seek re-election in November.

Kline said in an interview he still loves the Legislature, but at 69, is ready “to move on.”

“I want to spend the next period of my life spending time with my family and traveling,” Kline said. “I climbed Rainier nine times when I was younger. I think maybe I can do a 10th.”

A retired attorney and former lobbyist for the Mothers Against Drunk Driving, Kline was appointed to the Senate in 1997 to replace Dwight Pelz, who had been appointed to the Metropolitan King County Council (Pelz is now chairman of the state Democratic Party).

Since then, he has cultivated a reputation as a sharp-toothed fighter, sparring at times with everybody from anti-tax professional initiative promoter Tim Eyman to Gov. Gary Locke.

Kline is perhaps most famous for a 2007 confrontation with Eyman in which he said, “Answer the question, Tim. Where is the fat in the budget? You won’t answer the question, and the reason you won’t is that you’re a chicken. You’re a chicken. You are a coward.”

But he said he is most proud of a battle with Locke and then-Attorney General Chris Gregoire shortly after the Sept. 11, 2001, terrorist attacks.

At the time, Kline said, both Locke and Gregoire, and state House leaders, were pushing to create a new crime of “terrorism” that Kline found too broad, and to expand the authority of police to wiretap citizens.

After an intense, hourlong negotiation, Kline said he agreed to support a scaled-back version of the first bill in return for the other side dropping the second.

Then, Kline said, the House passed both of Locke’s bills anyway.

“They thought I was bluffing,” Kline said. “So we killed both of them. That’s what we did. We just killed them. We brought them up and voted them down, because the fact is, both of those bills would have done irreparable harm to the state.”

In recent years, Kline has successfully worked to strengthen drunken-driving laws and shorten prison time for nonviolent criminal offenders. He has also been among the Legislature’s biggest champions for more restrictions on gun ownership, although he acknowledged he has had “zero success” with that.

Asked to describe his style, Kline said “straightforward.”

Then he added, “yes, it’s true, I do not have a facility for keeping my mouth shut.”

Kline’s district, the 37th, is a solidly Democratic area that is currently represented by state Reps. Sharon Tomiko Santos and Eric Pettigrew.

Brian M. Rosenthal: 206-464-3195 or brosenthal@seattletimes.com. On Twitter @brianmrosenthal