King County Executive Ron Sims, a superdelegate for Hillary Clinton since last year, tonight endorsed Barack Obama. He said in a statement:

As a superdelegate and President of the National Democratic County Officials, I supported Senator Hillary Clinton early on and am truly honored to have been co-chair of her Washington State campaign. She is an extraordinary leader, and I have maintained my support for Senator Clinton through the grueling national primary and caucus process. Through it all I have been impressed by the wealth of riches we have had with two exceptional candidates. Now it is time for me to join other Democrats to unite behind Senator Obama. Senator Obama will bring much needed change and excitement to this country when he is elected President of the United States.

Sims becomes the first state superdelegate to switch in the drawn-out campaign for the Democratic nomination. Two superdelegates, Ed Cote, and Sharon Mast, have yet to say who they back.

Congressman Jay Inslee, a Clinton co-chair here along with Sims and former Gov. Gary Locke, is sticking with Clinton at least until tomorrow. He said in an e-mail:

This is an historic moment where two candidates have advanced historic causes, so we should all be proud of what Democrats have acheived. Sen. Clinton has asked for our thoughts and I will give her my advice privately tomorrow. I know we will be a united party for this noble cause.

Sims was a (relatively) early backer of Clinton. He endorsed her last September and was named to her Environment and Energy Task Force and was named a co-chairman of her state campaign.