The 1.3-million-member American Federation of State, County and Municipal Employees, the nation's largest public employee union, has lost about 10 percent of its active members since 2009. The National Education Association, which represents public school teachers, lost more than 100,000 members since 2010.
"I'm not going to be cocky about anything," said AFL-CIO political director Mike Podhorzer. "There are still plenty of Republicans in office and we don't expect them to change their spots overnight."
Next to winning Obama's re-election, defeating Proposition 32 in California was labor's top goal. Prohibiting unions from collecting money for political activities through paycheck deductions would have deprived them of tens of millions of dollars for donations to candidates and financing campaigns.
In New Hampshire, unions were worried that the state legislature had passed right-to-work measures in the past two legislative sessions. But lawmakers could not override a veto by Democratic Gov. John Lynch. Hassan's victory gives unions similar protection.
In Minnesota, gaining Democratic control of the state legislature could help the Service Employees International Union change a state law to allow the union to organize more than 12,000 day care providers in the state.
Perhaps the largest issue looming for public employee unions in the next few years is the shortfall in government pension systems, which have sunk deeper into the red as the recession has taken its toll. Cities and states around the country — led by Republicans and Democrats alike — have been reducing promised benefits to public workers and retirees as they attempt to cover shortfalls. States need about $1.4 trillion to fulfill their pension obligations, according to the Pew Center on the States.
Over the summer, the Governmental Accounting Standards Board approved new accounting rules for pensions that will make some underfunded plans look worse when the rules begin to go into effect late next year. State and local governments will have to print their total unfunded liability on the front of financial statements.
"It's going to help identify those plans in serious trouble, which could help policy makers and the public be aware of the need for action," said David Draine, a researcher who tracks pension changes at the Pew Center.
That could increase pressure on elected officials to reduce benefits and make bargaining more difficult for unions.