A political third force has sprung up in Seattle, intent on rescuing Washington's tradition of progressive state government from what voters here increasingly see as bankruptcy of the two major parties.

Splinter parties are nothing new in the West, where scattered factions of the left or right often have tried to establish themselves in the political order. Usually, they have quickly sunk from sight.

But the new "Washington Party" could be different: it is uniquely a revolt of the political center, of people whom former Republican governor Daniel Evans likes to call "passionate moderates."

Its draft statement, prepared by dissaffected activists from both political parties, seems an amalgam of Democratic and Republican principles, with a dash of Common Cause hopefulness. One of its five planks states that "free competition and monetary incentives for the individual are the heart of our economic system;" another, that "state government has an affirmative responsibility to help end racial and sexual discrimination in our society . . ."

The first, private meeting of the Washington Party was organized by Seattle city attorney Douglas N. Jewett, a one-time supporter of Democrat George McGovern who in 1976 managed the campaign of the moderately conservative GOP gubernatorial nominee, John Spellman. Among the 40 people at Jewett's home was Evans, four Seattle city councilmen, two labor union leaders and representatives of the city's black and Asian communities.

One of those attending described the assemblage as "the best political brains and the most committed persons in the state of Washington." A less upbeat assessment likened the group to a "warmed-over version of the Bull Moose Party."

The new force is a response to flamboyant, outspoken Democratic Gov. Dixy Lee Ray. Aggressively supportive of large-scale industrial development and nuclear power, Ray has recreated the state party in her own image.

In the process, she has won support of industrialists who previously backed Republican candidates. But she also has alienated those in the environmental wing of the Democratic Party, who say she is intent on making Washington a dumping ground for nuclear wastes, petrochemicals and super-tankers. At one point, speaking to an Olympia service club about nuclear hazards, she said that the atomic bombing of Hiroshima and Nagasaki in 1945 had "no genetic effects."

In the old days, dissident Democrats simply would have turned to Evans, who earned a reputation as one of the nation's most innovative and liberal Republican governors.

But Evans stepped down in 1978 after three terms and left the state GOP banner to King County (Seattle) executive Spellman, a colorless and efficient manager who some Republicans thought made Gerald Ford look charismatic by comparison. Despite a big lead in the early public opinion polls, Spellman lost to Ray. Now, he appears to be the likely candidate of his party again.

Spellman says his polls show him leading the governor by a wide margin, but a private survey by pollster Peter Hart for the incumbent forecast a second defeat for Spellman. Word of the Hart poll, leaked to newspapers, caused consternation among Ray's adversaries in both parties.

As an alternative to Spellman, a few Republicans have expressed interest in Secretary of State Bruce Chapman, a moderate of the Evans wing. But Chapman has little money and name recognition, and there are many who think a third-party option would be a better bet next year.

From an election-law standpoint, Washington is an ideal state for a third-party experiment. There is, most importantly, no party registration. All voters received the same primary ballot and can criss-cross at will, voting for a Democrat for one office and a Republican for another.

A third party could qualify a candidate by holding a convention in mid-July and have its nominees on the September primary ballot. If they received one percent of the vote, they would advance to the November runoff. Some politicians here, including Jewett, think Spellman might back out if Evans were nominated by the Washington Party. Such a turn of events would probably result in the nominations of Ray and any one of several possible Republican conservatives, and thus give Evans a reasonable shot at victory on the Washington Party ticket.

The hitch is that Evans, who leads Ray in the Hart poll, has said that he can "conceive of no possible circumstances" under which he would run again, either as a Republican or a new party candidate.

But in a long interview, centering on what he sees as increasing inability of both major parties to win public confidence, Evans said he feared that corporate and union power expressed through the fund-raising of political action committees has made it extremely difficult for governments to be responsive to public needs.

"We're seeing a renaissance of the old times where the railroads used to buy and sell the legislatures," Evans said.

What the former governor would prefer to do is work to strengthen the existing parties. However, Evans acknowledges that public trust in them is now so low that rehabilitation may be impossible.

What the former governor would prefer to do is work to strengthen the existing parties. However, Evans acknowledges that public trust in them is now so low that rehabilitation may be impossible.

"We may well be at the fairly unique time in our national history when people are ready for a third force," Evans said.

As Jewett sees it, such a force need not take on the traditional trappings and functions of the political party. Following the example of the volunteer groups that once played a vital role in California politics, it could instead serve as an endorsing organization, able to raise money for major-party candidates who shared the group's goals.

The gathering at Jewett's home in the hills of Lake Washington produced an ambivalent response from the participants. Many of them had come expecting a "draft Evans" meeting by some other name and were disappointed to find that Evans apparently didn't want to be drafted for a 1980 race. Others found they had grown interested in the notion of a third party for its own sake, believing that one could take hold in a state where both the official Democratic and Republican organizations had become little more than the playthings of well-known candidates.

The proposed Washington Party has already raised enough money from its would-be founders to poll the electorate on attitudes toward a third party. According to a provisional party charter drawn up by Jewett, membership would be open to anyone who contributed or raised $100 for the party, or who put in 16 hours at volunteer labor.

So conceived and organized, the city attorney believes, the Washington Party could prove a lasting alternative to established parties dominated by handfuls of contributors and a few large interests. And if Evans should decide that the "circumstances" in Washington had changed, the state indeed could show itself ready for a third force.