At issue is how the regulations impact union-sponsored health plans. They also want the subsidizes for low-income workers who enroll in the exchanges to be available to low-income union members who participate in union-sponsored health plans.
Here is one report from Fox News:
The AFL-CIO approved a resolution saying that President Obama's health care overhaul will drive up the costs of union-sponsored health plans to the point that workers and employers are forced to abandon them.
In a strongly worded resolution released Wednesday, the federation said that labor unions still support the Affordable Care Act's overall goals of reducing health costs and bringing coverage to all Americans, but added that the law is being implemented in a way that is "highly disruptive" to union health care plans.
Some individual unions have complained about the law's impact for months, but the resolution marks the first time the nation's largest labor federation has gone on record embracing that view. Unions were among the most enthusiastic backers of the law when it passed in 2010.
A labor official told The Associated Press that White House officials had been calling labor leaders for days to urge them not to voice their concerns in the form of a resolution. The official, who wasn't authorized to discuss the conversations publicly and requested anonymity, said many union leaders insisted that they wanted to highlight their concerns.
And here is the AFL-CIO post on the resolution where they identify it as calling for "fixes" in the act.