Democratic U.S. Rep. Jay Inslee said Saturday he is quitting Congress to devote himself full-time to becoming the state’s next governor.

“I am not one for half measures or half-hearted efforts,” Inslee said in a statement. “I am going to leave everything on the field. I am all in.”

Inslee is in his seventh term serving the 1st Congressional District, which includes south Snohomish County. He will leave office March 20 and the job will be vacant until voters in the newly configured congressional district elect a successor in November.

He entered the race to succeed Democratic Gov. Chris Gregoire last year. He is battling Republican Attorney General Rob McKenna in what is expected to be one of the closest gubernatorial contests in the country this year.

What Inslee called a “difficult decision” is not a big surprise. He and his advisers have been considering it for awhile as his campaign struggled to gain traction and McKenna’s campaign gelled.

Tactically, Inslee needs to begin cutting into McKenna’s advantage among independent voters. To do that, he must get outside the Puget Sound area and campaign in places where his name and political biography are unknown.

Inslee intends to do that.

“I am traveling everywhere in our state and I am going to listen to everybody,” Inslee said in a letter to supporters sent after his announcement. “I am getting up every morning, seven days a week, to go out and listen to the people of Washington about their needs, their ideas and their dreams.”

He’s wanted to minimize potential blowback from the public and Republicans.

By choosing to leave office after March 6, he doesn’t force the state to conduct a costly special election.

And his early departure will not end services for residents living in the current district. His offices in Shoreline, Poulsbo and Washington, D.C., will remain open and staff will continue serving constituents until 30 to 60 days following the November election.

Republicans, who said Inslee may be trying to disassociate himself from a very unpopular Congress criticized him for not finishing the job to which he was elected in 2010.

“It means he won’t have to take any controversial votes in Congress and it leaves the people of his congressional district without representation for eight months,” said Washington State Republican Party Chairman Kirby Wilbur.

“I promise we won’t let people forget that Jay Inslee is a congressman,” he said. “And maybe, just maybe, if he can focus on the governor’s race, he will come up with some ideas.”

McKenna jabbed at Inslee as well.

“I look forward to hearing Congressman Inslee explain how 15 years in Washington, D.C., have prepared him to lead our state, now that he is quitting Congress,” he said in a statement. “Our team has been waging a campaign of ideas since last June, yet the Congressman waited over seven months after announcing his candidacy to release any specific proposals.”

History was not on Inslee’s side if he stayed put.

Only once has Washington elected a sitting member of Congress to be governor. It happened in 1944 when Sen. Monrad Wallgren, a Democrat from Everett, won the job.

Quitting federal office can deliver dividends. In 2010, nine sitting members of Congress ran for governor and four won, according to a tally from Inslee’s campaign. Only two of the nine chose to leave early and both are now governors.

The Associated Press contributed to this report.

Jerry Cornfield; 360-352-8623; jcornfield@heraldnet.com