SEATTLE (AP) — A new lawsuit is challenging Seattle's first-in-the-nation voucher system for publicly financing political campaigns.

The libertarian-leaning law firm Pacific Legal Foundation is suing the city over its new "democracy voucher" program, which was passed by voters in 2015 and is being used for the first time in this year's City Council races.

Under the program, Seattle's voters decided to tax themselves $3 million a year in exchange for four $25 vouchers that they can sign over to candidates. Supporters say it's a novel way to counter the effect of big money in politics and to help lesser-known candidates communicate their views.

But the lawsuit filed in King County Superior Court Wednesday says it forces people to pay taxes to support candidates they don't necessarily agree with — in violation of their free-speech rights.