Representative Jay Inslee said on Saturday he would step down from Congress later this month to focus full time on what is expected to be a tight race for governor of Washington state.
Inslee, a Washington Democrat who has served in Congress since 1999, said his resignation is effective March 20.
He is running against Republican Rob McKenna, the state's Attorney General, in a gubernatorial race to replace Democratic incumbent Christine Gregoire.
Two recent opinion polls showed the rivals in a dead heat, after surveys earlier in the year gave McKenna a clear lead.
"I am excited about focusing full-time on talking about my job-creation agenda and building a new economy for Washington state," Inslee said in a statement.
"We have a great chance to seize our own destiny, build our own industries, and create our own technological revolutions right here at home," he added.
Inslee said he took the decision to step down "very recently" after watching Republican presidential candidates pushing a "divisive social issues agenda."
He said seeing state Republicans pursue plans to slash state education funding was also a factor.
"It was a difficult decision, but what I need to do right now is focus all my attention on talking to people about what's really important - creating jobs and growing our economy," he added.
Inslee announced he would run for governor after Gregoire said last June she would not seek a third term in 2012.
Gregoire has said she is retiring to spend more time with her husband Mike and two daughters.
A Grove Insight poll on March 6 had rivals Inslee and McKenna in a dead heat, each with 38 percent support. And on February 22, a PPP poll had them tied at 42 percent.
They followed polls by Survey USA and Elway earlier in February, which had McKenna leading by 10 and nine points respectively.
(Reporting by Tim Gaynor; Editing by Greg McCune)