Sen. John Thune, R-S.D., introduced legislation Monday, preventing the administration from providing a special fix to union-backed multi-employer health insurance plans, also known as "Taft-Hartley plans".

White House officials have been in intense behind the scenes talks with Big Labor to do just that because provisions of the Affordable Care Act — aka Obamacare — will force employers to limit the plans or even pull out altogether.

Thune said: "Despite championing ObamaCare’s passage in 2010, union leaders are now awaking to the ugly reality of ObamaCare that most Americans have predicted all along, including higher health care costs. Now that the full consequences of the Democrats’ law are nearing, these same union leaders are seeking a special backroom deal from the White House. Rather than take hard-earned money from taxpayers to subsidize union health care plans, the Obama administration should give all Americans a break by permanently delaying this train wreck.”

Unions have been pushing the administration to extend the law's insurance subsidies to the multi-employer plans. The White House has resisted doing this though because it would cause the law's costs to soar even further. One estimate put the cost at $187 billion over a decade.

Tensions between President Obama and union leaders have been boiling over on the subject. At the AFL-CIO's quadrennial convention in Los Angeles, delegates passed a resolution calling Obamacare a threat to multi-employer plans and calling on Congress to change the law. This happened despite lobbying from the White House to table the measure.