President Obama will meet with union leaders at the White House on Friday to quell growing concerns over Obamacare after taking a barrage of friendly fire from labor groups.

The AFL-CIO passed a resolution at its annual convention earlier this week criticizing elements of the president’s healthcare reform law, charging that the “highly disruptive” Affordable Care Act would increase the costs of union-sponsored health plans.

Some earlier drafts of the resolution even called for repeal of the health care law — barring additional changes to the legislation — highlighting worries among some of the president’s staunchest liberal supporters.

The dispute comes at a critical time: As the administration prepares to begin enrolling consumers in Obamacare’s new insurance exchanges in October, the White House can ill afford a revolt from the left.

Polls show much of the American public remains confused by the health law’s provisions, a reality that Republicans hope to tap for maximum political gain heading into the 2014 elections. Many Democratic lawmakers have already expressed concerns that a bumpy rollout could hurt them in the midterms.

Union frustration is simmering despite extensive loyalty to the White House.

“The unions have this feeling that they have funded a lot of political candidates and haven’t gotten any real policies to show for it,” said Ryan Lamare, an associate professor of labor studies and employment relations at Pennsylvania State University. “This is a way for them to say: ‘You have to listen to us.’”

Labor interests are calling for a major overhaul of Obamacare, saying the president should approve rule changes that would give union members subsidies to help pay for their healthcare plans.

Without those revisions, public employees groups say employers will hire fewer union workers.

Union leaders are also incensed by the administration’s decision to delay until 2015 the requirement for most employers to provide health insurance plans for their workers, as well as the cap on out-of-pocket costs on medical care.

And outside of healthcare, big labor and their allies are still bristling over the White House’s lukewarm support for card-check legislation, which would help reverse declining union membership. The legislation died on Capitol Hill and the administration has done little to resurrect the initiative.

White House officials sought out labor leaders repeatedly in recent days, urging them to soften their rhetoric against Obamacare, union officials acknowledged.

“Of course they’re reaching out to us,” one AFL-CIO official said of the administration. “We could be [the White House’s] worst nightmare on this. If we don’t get action, they have a real problem.”

Highlighting that sentiment, Republicans are now accusing the White House of partnering with unions in a sweetheart deal.

“We know big labor is leaning on the president to let them rewrite the same law they helped ram through," Senate Minority Leader Mitch McConnell, R-Ky., said from the Senate floor Thursday. "And apparently he's listening to them. What about everybody else that's not in big labor?"

Earlier in the week, Sen. John Thune, R-S.D., introduced the “Union Bailout Prevention Act,” which he said would prevent labor groups from receiving special exemptions for healthcare costs not available to the rest of the public.

The White House is in a difficult spot, having to appease critical supporters while not appearing to grant them special favors or undermining confidence in the health law.

Addressing the AFL-CIO convention this week, Labor Secretary Thomas Perez acknowledged that “challenges remain” in launching the most comprehensive overhaul to the healthcare system since Medicare in 1965.