PORTLAND — Two teacher unions have filed another lawsuit in their long battle with political activist Bill Sizemore.

The Oregon Education Association and the American Federation of Teachers-Oregon accuse Sizemore of illegally hiding assets in the name of his wife, Cindy.

The unions claim Sizemore was managing a petition signature campaign for more than half a dozen initiatives while a Nevada company called American Tax Research Foundation was paying Cindy Sizemore for the work.

The lawsuit, filed Thursday in Multnomah County Circuit Court, accuses the Sizemores and the foundation of conspiring to funnel money illegally to the Sizemores.

“Mr. Sizemore continues to think and act like he is above the law,” said OEA President Larry Wolf.

Sizemore denied the claims and accused the unions of using the courts to try to chase him out of politics.

“That’s what this is all about — trying to stop me from putting measures on the ballot they don’t like,” Sizemore said.

Efforts to find a telephone number for the foundation were unsuccessful. E-mail sent to separate addresses at its Web site were returned as “unknown.”

The foundation is headquartered in Nevada, home of Loren Parks, owner of an Oregon medical equipment company who has in years past financed several of Sizemore’s measures. “It is not his baby,” Sizemore said, but he said he wouldn’t say that Parks hadn’t donated money to it.

A form filed with the Nevada secretary of state’s office in January 2006 for a nonprofit corporation lists a “W.L. Sizemore” as a member of the board of directors for the foundation, based in Las Vegas.

Sizemore won a major success as an anti-tax crusader in the early 1990s with a statewide property tax limit measure. He ran, unsuccessfully, for governor. The unions went to court in 2002 and won a $2.5 million judgment in a racketeering and fraud lawsuit against his political organization, the Oregon Taxpayers United, now defunct.

The Oregon Court of Appeals ruled that Sizemore was not personally liable for the judgment. The unions have appealed to the Oregon Supreme Court.

Earlier this year, Sizemore was ordered to pay $125,000 in union attorney fees for violating an injunction restricting his initiative business. The lawsuit filed Thursday is aimed only at the attorney fees.

Sizemore’s lawyer, Gregory Byrne, says he will ask a judge to dismiss the latest lawsuit.

“As long as Bill keeps running measures that unions think are going to undermine their power, they’re going to keep harassing him,” Byrne said.

Sizemore is backing several initiatives for the 2008 ballot, including an unlimited state deduction for federal taxes, requiring English-only classes for schools, and a teacher merit pay plan that ties raises to student performance on tests.

Wolf said the lawsuit is “not persecution of any kind.”

“This is his livelihood, this is what he likes to do — we’re not against that,” Wolf said. “But when he owes organizations money, and there appears to be money coming in the back door, that’s when we have to question it.”