Americans for Prosperity Washington, the local chapter of the Tea Party political committee backed by the billionaire Koch family, are already the subject of a complaint filed at the state Public Disclosure Commission. And now it looks like the state Democrats may up the ante.

Sen. Karen Keiser (D-33) tells PubliCola she is planning to send a letter to state Attorney General Rob McKenna next week to pursue a case against the group. "These national groups, under these Citizens United rules, are thumbing their noses at our state."

Citizens United is the Supreme Court ruling that allowed corporations to spend unlimited dollars on independent campaign ads. Taking advantage of rules that keep donors to nonprofits secret, big spenders have been pouring money into front groups. (I was on KUOW yesterday talking about Citizens United and its impact on the current election.)

The mystery spending has been mostly confined to federal races—like the $6.6 million in undisclosed money that has funded attack ads against U.S. Sen. Patty Murray—but taking its cue from the national group, AFP's Washington chapter, AFPW, is doing ads against state senate candidates without disclosing its funders.

We have a call in to AFPW's local director, former KVI host Kirby Wilbur.

Last month, the Sierra Club filed a complaint against AFPW for not registering as a political committee or disclosing its donors—even though AFPW did a mailer against state senate incumbent Eric Oemig (D-45).

And as we've reported, AFPW has also done a mailer against state Sen. Rodney Tom (D-48).

It turns out AFPW has done several hit pieces against state senate Democrats, including Sens. Chris Marr (D-6), Tracey Eide (D-30), Randy Gordon (D-41), and Claudia Kauffman (D-47).

"This is a real violation of state law," she says. "We require that contributions be disclosed, and they are not. They are carpet bombing our state and failing to abide by our law. I think there is a court case here. I will be asking Attorney General [Rob] McKenna pursue this to enforce our laws."

Sen. Keiser estimates that doing mail pieces in this many races probably costs about half a million dollars.

These are seven critical races for the Democrats—all vulnerable candidates that could lose, which would hand the state senate over to the GOP. (The current split is 31-18.)