The President's health care overhaul is now frustrating labor unions that once supported it.
Retail, construction and trade union leaders say Obamacare is making their multi-employer plans more expensive.
The higher costs could force some employers to abandon union plans to save money.
This could send millions of union members to less comprehensive health coverage in state exchanges.
The issue could create a political headache next year for Democrats facing re-election if disgruntled union members believe the Obama administration and Congress aren't working to fix the problem.
"It makes an untruth out of what the president said, that if you like your insurance, you could keep it," said Joe Hansen, president of the United Food and Commercial Workers International Union. "That is not going to be true for millions of workers now."
The problem lies in the unique multi-employer health plans that cover union workers with seasonal or temporary employment.
Those plans were already more expensive than most health plans provided by employers. The Affordable Care Act has added to that cost -- for the unions' and other plans by raising the dependent coverage age to 26, eliminating annual or lifetime coverage limits and requiring coverage of pre-existing conditions.
"We're concerned that employers will be increasingly tempted to drop coverage through our plans and let our members fend for themselves on the health exchanges," said David Treanor, director of health care initiatives at the Operating Engineers union.
The White House continues to defend Obamacare, but there is concern about angering a powerful political constituency.