MADISON, Wis. — More taxpayer dollars would be directed toward Wisconsin Supreme Court campaigns in an effort to blunt the impact of special-interest money in the officially nonpartisan races under a bill passed by the Democratic-controlled Legislature.

Supporters said the measure passed Nov. 5 would give candidates a new revenue stream and reduce fears that special-interest groups control the court through campaign contributions.

“Citizens need their high court to be completely above board,” said the bill’s main author, Sen. Pat Kreitlow, D-Chippewa Falls. “A well-padded checkbook has no place in that chamber.”

Critics blasted the measure, S.B. 40, saying it did not offer enough money to attract candidates or address so-called issue ads, unregulated commercials from third-party groups that may attack or praise a candidate’s stance on particular issues but don’t expressly advocate a vote for or against the candidate or his or her opponent.

“As much as they may try, more competitive and more expensive state Supreme Court races are here to stay,” said Joe Murray, a lobbyist for the Wisconsin Realtors Association, which opposes the bill. “There’s too much at stake. They may want the old days, but I don’t think they can recreate them.”

The state Senate and Assembly both passed the bill on Nov. 5, the last day of session for the year. Gov. Jim Doyle, a Democrat, has said he would sign the measure.

Supreme Court races in Wisconsin have become big-money affairs, raising questions about who justices owe and whether they can set those connections aside when they rule on cases.

The push for reform began after Annette Ziegler and Michael Gableman won election in 2007 and 2008 in races marked by big spending by outside groups. Wisconsin Manufacturers and Commerce, the state’s largest business group, alone spent an estimated $4 million to help Ziegler and Gableman combined, according to the Wisconsin Democracy Campaign, a government watchdog group that has registered in favor of the bill.

Late last month the Supreme Court adopted rules proposed by the business group and realtors to allow judges to hear cases involving their biggest campaign donors.

Reformers say public campaign financing for court races would remove the stigma that special interests own the justices.

The state already offers candidates public money for their campaigns through a fund built with a voluntary $1 checkoff on people’s tax returns. That system offers Supreme Court candidates a maximum of $97,000 and limits their total spending to $215,625.

The fund, though, also covers candidates for other statewide offices, such as the attorney general and governor. State election officials have had to prorate Supreme Court candidate funding since 1989.

The new bill would create a $3 voluntary tax checkoff. One dollar would go to the existing campaign account. The remaining $2 would go to a new account dubbed the Democracy Trust Fund.

The money in that account would go exclusively to Supreme Court candidates. If the fund can’t cover every candidate, money will come out of the state’s general fund.

Eligible candidates could get a $100,000 grant for a primary campaign and another $300,000 grant for a general election run. If their opponents or groups that expressly support their opponents outspend them by a certain percentage, the candidates would get more state money to match that amount.

“This would enable candidates to be free of this money race,” said Mike McCabe, executive director of the Wisconsin Democracy Campaign.

The system could cost the state about $3.5 million per election, according to the Legislative Fiscal Bureau.

The realtors’ Murray said the state, which faced a $6.6 billion deficit in its last budget, can’t afford that. Even if lawmakers can generate the grants, they don’t provide enough money to run a realistic statewide campaign and candidates won’t participate.

“The only people running will be wealthy people,” Murray said.

Sen. Mike Ellis, R-Neenah, complained the bill does nothing to address issue ads. The ads for years have been a sore spot for politicians, who complain mysterious groups use the ads to attack them with impunity.

Interest groups will still outspend publicly financed candidates by spending right up to the level that triggers matching funds but not go beyond it, he added.

“Let’s stop fooling the public. Don’t we want to take back these elections?” Ellis said.

Kreitlow acknowledged that the bill wasn’t perfect but called it a start.