Big Island state Sen. Paul Whalen announced yesterday he will not run for re-election this year, leaving the state GOP with the challenge of saving the only state seat it holds on the Neighbor Islands.

Whalen, R-3rd (Kohala, Kona, Ka'u), told colleagues in a short speech on the Senate floor that he wanted to end rumors about his future.

"After 12 years in office, I appreciate the opportunity my constituents have given me and I appreciate the friendships I've developed here at the House and the Senate. But I just wanted to announce — to stop the rumors — I will not be running for re-election," he said.

Whalen, an attorney, has served in the Senate since 2002. He previously served in the state House.

Whalen had said in November he was interested in the state Office of Planning post, but the Lingle administration chose Moloka'i community planner Abbey Seth Mayer for the position.

State Rep. Josh Green, D-6th (N. Kona, Keauhou, Kailua, Kona), announced last year his intention to run in Whalen's district and has raised about $90,000 for his campaign. Green recently had presumed Whalen was not running because the senator had not been actively raising money.

Willes Lee, the state's GOP chairman, said the party considers the west side Senate district competitive because many voters are independents and it has been trending Republican. He said the party has not identified a candidate.

"I actually think this might scare Josh a little bit," Lee said of the campaign for an open seat.

Green said Whalen's announcement would not change how he is approaching the campaign. "It makes no difference at all," he said. "I'm still going to work twice as hard as I've ever had before."

Reach Derrick DePledge at ddepledge@honoluluadvertiser.com.