Since Obamacare became law, employers have been griping about the definition of "full time" work - 30 hours a week. It means that any employee working 30 hours a week or more had to be covered by health insurance. This has resulted in more part time workers being hired and employers cutting back the hours of some workers to under 30.

Republicans see an opening to cripple Obamacare by boosting the definition of full time to 40 hours a week. To that end, bills have been introduced in both houses of Congress and the business lobbies are gearing up to support them.

The Hill:

In the coming days, both the House and Senate will take action on bipartisan bills that would modify the full-time employee standard, a component of the law’s employer mandate. But corporate lobbyists now trying to build support among lawmakers will have to overcome objections from labor unions and President Obama.

Under the healthcare law, large employers must provide insurance to employees working full time — defined in ObamaCare as at least 30 hours per week — or face a penalty. Senators on Wednesday will offer up a bill that aims to change that threshold to 40 hours. The House will take a vote on similar legislation on Thursday.

“In the last Congress, while there was strong acceptance of the need to do this, the decision about when to do it was calculated based on ACA bigger [Affordable Care Act] politics,” said Scott DeFife, executive vice president of policy and government affairs for the National Restaurant Association. “I think now there is an acceptance that changes can be made to the ACA, since it’s happening so fast.”

The restaurants, joined by the International Franchise Association, the U.S. Chamber of Commerce, the American Hotel & Lodging Association, and several others have launched a campaign dubbed “More Time for Full Time” to encourage the change. 

In addition to teams of lobbyists mobilized by the organizations, the initiative attempts to showcase support among constituents for the measure.

Other supporters, such as the National Federation of Independent Businesses, are acting separately. Together, the organizations intend to flood Capitol Hill with letters, phone calls and visits to help push the measure through. 

A member of the franchisers association who owns a Fargo, N.D.-based retail chain penned an op-ed over the holiday recess opposing the full-time definition, a nudge to Democratic Sen. Heidi Heitkamp, who represents red-state North Dakota.

“If the workweek is defined as 30 hours instead of the traditional 40 hours, we will be inclined to hire more people part time rather than at the full-time wages they’d prefer to receive,” business owner Ciara Stockeland wrote in the op-ed, outlining the key argument of the bill’s supporters. “No one wins, and the economy is quickly affected.”

The move would not necessarily allow employers to cut a few hours from 40 hour a week employees and avoid the business mandate. That's because part of the calculus for covering workers is total hours worked by employees. Instead, the raising of the workweek requirement would give more freedom to employers to "manage your workforce in a way that is true to the pulse of the industry,” according to one restaurant industry lobbyist.

President Obama will probably veto the legislation. But there may be a chance to override that veto as many Democrats support the idea.

This is the first salvo fired against Obamacare by the Republican congress. Expect many other attacks as the GOP looks to whittle Obamacare away piece by piece.