In response to a similar crackdown on public employees' collective bargaining rights in Wisconsin — done as a budget-cutting measure — Wisconsin Democrats and labor leaders launched a recall campaign to win control of the state Senate from Republicans. They fell short in Republican-majority state Senate district races, but are more confident of the statewide referendum in Ohio.

     "We will, I believe, win that citizens veto," AFL-CIO president Richard Trumka said of the Ohio vote in a recent speech at the Brookings Institution in Washington.

     The AFL-CIO alone poured more than $5.5 million into the Wisconsin effort and similar expenditures are planned for Ohio. Insiders are predicting the ballot battle could cost more than the $33 million spent in last year's race for Ohio governor.

     Unlike the law in Wisconsin, Ohio's measure curbing union rights includes police and firefighters, who tend to be more popular with independent and conservative voters. Ohio's firefighters have been featured prominently in television ads supporting the referendum. The nation's largest firefighters union, the International Association of Fire Fighters, has spent about $1 million so far in Ohio.

     "If we were to win, I think it would be a major encouragement that will be hugely beneficial, not only to Democrats running for the state House and state Senate, but I think it would be a huge benefit to Senator (Sherrod) Brown and to President Obama," former Gov. Ted Strickland told The Associated Press.

     But Strickland also warned that a loss on the referendum "would be a major blow to the Democratic Party going forward."

     The repeal effort is popular now in Ohio. A Quinnipiac University poll last month showed 51 percent of Ohio voters would repeal the law, and another 38 percent support the overhaul. But most observers expect those numbers to tighten as the conservative group Building a Better Ohio, which backs the law, ramps up spending on television ads. The bill's supporters received a boost this weekend when the editorial board of The Plain Dealer, a Cleveland newspaper based in the traditionally Democratic stronghold of Cuyahoga County, endorsed a "yes" vote to keep the law.

     Democrats and unions hope to tap into the 1.3 million Ohioans who signed petitions to get the referendum on November ballots. And they see Ohio as a chance to rehearse their get-out-the-vote efforts for next year's presidential campaign.

     "The referendum vote in Ohio is huge," former AFL-CIO political director Steve Rosenthal said. "A victory on the initiative will provide a huge boost to labor and progressives on the whole. A loss would hurt, but the organizational infrastructure that has been built for this campaign will carry over into a major effort to win in 2012."

     Republicans contend this year's election issue will be a distant memory by the time Ohioans cast their ballots for president.

     "I don't think there's a carry-over effect," said Kevin DeWine, the state's Republican Party chairman. "You can't look at an election in one year and think that it's going to have an impact on the election in the next year, in part because I think the issues are different."

     Jim Ruvolo, former Ohio Democratic Party chairman now working as a political consultant, agreed that the referendum would not be a very good predictor of the 2012 races, but said it might ignite Democratic enthusiasm.

     "People will be saying 'See we can win, we can beat them,'" Ruvolo said.

     With Obama's state approval ratings lackluster, there's no doubt losing on a statewide level would be a significant setback for unions and Democrats.

     As a practical measure, Ohio's public employee unions are expected to lose members once the law goes into effect, sapping both organizational clout and monetary resources. And it could send another message to other GOP lawmakers — that passage of time and continued economic problems has made voters less sympathetic to unions' desires.

     Obama's re-election campaign has largely stayed out of Ohio's union law repeal push, though his supporters have joined labor groups and others in an effort to ask voters in 2012 to overturn the state's new election law, which shortens the early voting timeframe.

     Any momentum the November referendum creates for Obama hinges on whether labor, Democrats and community groups can keep working together, said John Russo, a labor studies professor at Youngstown State University.

     Competing interests within such organizations can make rallying around a single candidate more difficult, he said.

     "He (Obama) can use it, but can he hold it together is a different story," Russo said. "He has to be able to take that enthusiasm, that set of ideas, those narratives and incorporate them into his own campaign."

     ___

     Hananel reported from Washington. Associated Press writer Ken Thomas also contributed to this report.