Tim Eyman's initiative campaign to use sales tax to audit state and local governments has received a nearly $275,000 boost from an investment adviser who said he helped craft Initiative 900.

Michael Dunmire of Woodinville has given Eyman's political-action committee Voters Want More Choices $273,493 over the past year, including an $80,000 donation last month.

It's the largest donation, by far, for the initiative king's campaign.

"Washington's been good to me, and I've been looking for a way to give something back to Washington state," said Dunmire, 60. "Eyman seems to get things done, and that's appealing."

Washington legislators passed their own performance-audit bill this session hoping to blunt Eyman's, whose initiative would authorize the state auditor to do performance audits of state and local governments, financed by a 0.01 percent sales tax to generate $10 million a year.

Eyman has called the legislative audit bill "toothless" because it leaves legislators in control of how much money would be spent on the audits and who would perform them.

A road bill passed by the state Senate this week includes a provision for independent performance audits.

Dunmire owns a company called Benchmark Plus, founded in 1997. Before that he was president of Paradigm Partners, another investment company, and vice president of the Frank Russell Co., also an investment firm.

Dunmire said he helped Eyman draft I-900, and the two had met when Dunmire contributed to an earlier Eyman initiative.

Last year's initiative that would have increased the sales tax for education was what fueled his interest and led to the big donations to I-900. He said he thought the measure, which was eventually defeated, lacked accountability.

"I'm a conservative and I don't know any people who are against education, but they want to know how their money is spent before they put their dollars into it," Dunmire said.

He said the initiative was also conceived in part because of the financial troubles of Sound Transit, another Eyman target.

"How can it conceivably be so far off in the estimate?" Dunmire said. "If a business made that mistake, it would be bankrupt."

Eyman said the real genesis of the performance audits was the conservative Evergreen Freedom Foundation, but he said Dunmire's contribution is huge.

"There's no doubt he stepped up to the plate big time," said Eyman, adding that he hopes Dunmire's contribution will encourage others to give to his initiative.

Dunmire said he is willing to give more money. "The limit is how long I live," he said.

Dunmire, who has been in the investment business since 1970, moved to Seattle in 1975 from New York. He said he visited the state on a dare from a friend in Wenatchee. "He said it was a utopia and I said it can't be as beautiful as he said. I came here on vacation and moved here. I have web feet. I love it."

Dunmire said his contribution will help pay for signature gatherers. The measure needs 225,000 valid signatures by July 8 to qualify for the November ballot. Eyman would say only that he's making "good progress" on signature-gathering.

He said the fact the Legislature passed a performance-audit bill will only make his initiative more timely.

"This will make the debate that much more exciting," he said, "whether the Olympia approach is the right way, or the citizen solution is the right way. We think voters want the real deal. I'm excited the Legislature proposed their Olympia sham approach."

Susan Gilmore: 206-464-2054 or sgilmore@seattletimes.com