(Bloomberg) -- Republicans, newly in charge of the House and Senate, begin their campaign to dismantle PPACA with a vote this week to ease the law’s requirement that large employers give health insurance to full-time workers. Under the Patient Protection and Affordable Care Act, companies with 50 or more employees were supposed to offer insurance to anyone working 30 hours or more a week, starting last year. The Republican bill would raise that threshold to 40 hours a week, requiring businesses to cover fewer employees. Republicans continue to maintain that the health law must be repealed entirely, even as coverage under the measure grows. At least 7.1 million people are enrolled in private plans sold under the law so far in 2015, and another 9.7 million have been added to Medicaid, the program for low-income people. “At a minimum, we are going to strip out the worst parts,” Sen. John Barrasso, a Wyoming Republican, said on Fox News today. The Republican effort would undo a requirement that the Obama administration has already delayed twice on its own. No business had to comply until this year, when those with 100 workers or more must cover at least 70 percent of employees. The mandate won’t apply to smaller employers until 2016. The president will likely threaten to veto legislation to change the full-time hours threshold before the House is scheduled to vote Jan. 8, a White House official said. The person asked not to be identified because the veto threat isn’t yet official. Setting the threshold for full-time employment at 30 hours has hurt part-time workers, Barrasso said, by encouraging companies to cut workers’ hours. Working hours“It’s hurt people’s take-home pay,” Barrasso said on Fox News. “It made people that work part-time have their hours cut to less than 30 hours a week.” Obama threatened to veto similar legislation the House considered in April. At the time, the White House said the bill “would weaken a provision of the Affordable Care Act that keeps employers from dropping health insurance coverage and shifting the cost to taxpayers.” The change would increase the deficit by $74 billion over 10 years and cause about 1 million people who have coverage now to lose their employer-provided health insurance, the White House said. There is some Democratic support for changing the threshold, as well as some Republican opposition. Senator Joe Donnelly, an Indiana Democrat, will introduce legislation tomorrow mirroring the House bill, with Republican Susan Collins of Maine. GOP oppositionYuval Levin, a former White House official under President George W. Bush who is influential among congressional Republicans, wrote in November that the change “would likely put far, far more people at risk of having their hours cut than leaving it at 30 hours.” Only about 7 percent of employees work 30 to 34 hours per week, Paul Van de Water, an analyst at the Center on Budget and Policy Priorities, a Washington research group that advocates for low-income people. More than 44 percent of employees work 40 to 44 hours a week, he said in a report today that criticized the bill. “It’s the present legislation, not health reform, that threatens the traditional 40-hour work week the legislation’s sponsors say they want to protect,” he wrote.