By crisis, he means myriad setbacks, including a steady loss of union membership, frequent defeats in organizing drives and unions being forced to accept multiyear wage freezes. Not only have labor leaders faced the embarrassing enactment of anti-union legislation in onetime labor strongholds like Wisconsin and Michigan, but they could not even win passage of legislation making it easier to unionize when President Obama was elected and the Democrats controlled the House and Senate.

In language far different from decades past — when labor often talked with ‘we’ll get it done ourselves’ bravado — Mr. Trumka said: “It’s pretty obvious to all of our progressive partners that none of us can do it alone. If we’re going to change the political and economic environment, it’s going to take us all working together.”

Gary N. Chaison, an industrial relations professor at Clark University, said: “Unions are thrashing around looking for answers. It just might prove successful from the very fact that there is great desperation to it. There’s a sense that this is make-or-break time for labor. Either major things are done, or it will be too late to resuscitate the labor movement.”

Labor’s reinvention process is taking many forms. The A.F.L.-C.I.O. has set up a dozen committees — of historians, young workers, Web experts, pollsters — to propose ways to reinvent labor. Our Walmart, a union-backed group of Walmart employees, has held repeated protests in the hope of somehow finding pressure points to persuade the giant retailer to improve pay and benefits. The Service Employees International Union helped organize a wave of one-day strikes at fast-food restaurants to create a nationwide movement of low-wage workers with the aim of pressuring McDonald’s, Subway and other chains to raise wages.