But unions are being spread thin as they deal with a new wave of measures they say are designed to weaken their clout. Indiana passed a right-to-work measure earlier this month, and Republicans in New Hampshire are pushing a similar bill. Legislatures in Arizona and Utah are weighing measures to limit bargaining rights for their public employees.
"Part of the Republican strategy is to try to bleed us," said Mike Podhorzer, political director of the AFL-CIO. "There are certainly more union members now who understand the importance of political engagement and are willing to go door-to-door and make phone calls and do campaigns."
Tim Phillips, president of the conservative anti-tax and anti-regulation group Americans for Prosperity, denied any grand strategy to weaken unions. His group, founded with the support of billionaire brothers Charles and David Koch, spends millions on anti-Obama and anti-union ads across the country.
"It's not accurate to say there's some master plan to drain resources," Phillips said. "These are genuine public policy efforts."
But Phillips said he thinks that, for the first time, unions have to confront organized grassroots opposition in a number of states.
"And Americans for Prosperity is absolutely a key component in that," Phillips said. "The unions have always had the advantage and we are now matching them."
... The AFL-CIO is following a new strategy outlined last summer to contribute less money to specific candidates and spend more on building its infrastructure. The goal is to lay a foundation for year-round mobilization that keeps going in the months following an election. Competing for the union money are the various races, from president to state lawmaker.
The new strategy emerged after some unions grew frustrated last year that Obama and Democrats in Congress were not doing enough to stand up for labor's agenda. But leaders say union members have become more enthusiastic about Obama since the president increased his focus on job creation.
The AFL-CIO also started its own labor super PAC, which allows it to raise unlimited amounts of money and mobilize support beyond its traditional base. The new super PAC has already pulled in $3.7 million.