OLYMPIA, Wash. (AP) — Democrats dominated much of Washington's election on Tuesday night, triumphing in several key races and claiming an early lead in the state's costly campaign for governor.

Jay Inslee, a former Democratic congressman, held 52 percent of the vote in the gubernatorial race as Republican Rob McKenna struggled in the population-rich King County. McKenna, seeking to become the first Republican to win the seat in more than three decades, asked his supporters to wait a few more days as mail ballots continued to arrive at county offices.

"This year, it will be worth the wait," McKenna said.

Although some races remain undecided, Democrats in Washington won big in key federal contests and were in position to potentially claim every statewide executive office — something they haven't done since the 1960s. Republicans held a very slight lead in only one statewide race — secretary of state — and that's an office they've held continuously since 1965. Democrat Bob Ferguson led Republican Reagan Dunn in the hard fought attorney general's race.

Democrats also found success in some of the top ballot measures. They had endorsed a proposal to legalize marijuana, which passed, and aided a measure to approve same-sex marriage, which held a lead.

Dwight Pelz, chairman of the Washington State Democrats, said he was very excited by the results. He doubted that McKenna could flip the numbers in the govenror's race, given the size of Inslee's lead and how poorly the Republican was performing in King County.

"It's a good day for Democrats across the country," Pelz said "And if we can win the governor's' seat, it would be a pretty good sweep for us here."

Perhaps the best consolation to conservatives was the passage of an initiative that requires lawmakers to have a two-thirds majority in order to raise taxes. That rule provides the GOP with the power to block tax-raising budgets in Olympia, although the state Supreme Court is currently considering whether it is constitutional. Another measure to develop charter schools in the state was in a toss-up Tuesday night.

McKenna was supposed to be the biggest Republican triumph, as he had been steadily building his political reputation for years and developing a deep grasp of the issues facing state government. The race was viewed as one of the most competitive gubernatorial contests in the country, with the campaigns and outside political groups raising and spending some $40 million in the race.

As of Tuesday night, hundreds of thousands of ballots remained uncounted while others had yet to arrive at election offices around the state.

Republicans last won a governor's race in the state in 1980, when John Spellman was elected. Voters ousted Spellman at the end of his first term, around the time McKenna was student body president at the University of Washington.

The GOP has come close in some elections, most notably the 2004 race in which Dino Rossi lost to current Gov. Christine Gregoire by 133 votes.

Republicans had been cultivating McKenna as a potential gubernatorial candidate, as he worked his way from the King County Council to attorney general. In that seat, he won 59 percent of the vote in 2008.

Inslee, meanwhile, took his first run at the governor's seat in 1996 but lost in a primary to eventual Gov. Gary Locke. He also bounced back from a 1994 defeat when he was serving as a congressman on the eastern side of the state and eventually won a new seat in Congress after his family moved west to Bainbridge Island.

Inslee held that congressional seat for a decade, becoming a leader in clean energy issues.

Clean energy also became a focus of Inslee's campaign for governor this year. He vowed to focus investments on that industry and others — such as life sciences and agriculture — to stimulate job growth.

To deal with Washington's unbalanced budget, Inslee said the state would bring in extra money from economic growth. He also vowed to seek savings in the health care industry and make government more efficient by following "lean management" practices.

McKenna, meanwhile, repeatedly noted that Olympia had been guided by Democrats for years and that the percentage of money going to education has shrunk under their watch. He vowed to cap non-education spending growth at 6 percent per biennium while also seeking improvements in health care costs and government efficiency.

Gregoire has been skeptical about whether McKenna and Inslee's budget ideas are viable, and she believes new tax revenue is necessary.

___

AP Writer Mike Baker can be reached on Facebook: http://on.fb.me/HiPpEV