Millions more American workers will soon be eligible for overtime pay under a rule being finalized Wednesday by the Labor Department.

The rule says anyone who makes less than $47,476 per year must receive time-and-a-half pay for hours worked beyond 40 hours a week. That's roughly double the current threshold of $23,660.

The measure is one of the most sweeping moves the Obama administration has made so far in its efforts to boost slow-growing incomes. But it's sure to face opposition from some business owners.

According to the Labor Department, the higher income threshold will make 4.2 million salaried workers newly eligible for overtime pay. The rule could also benefit millions of others who are already technically eligible but not receiving overtime.

The Two-Way

Debate Begins: New OT Rules Will Raise Wages — Or Kill Jobs

"Our whole mission here is about strengthening and growing the middle class," Labor Secretary Tom Perez told NPR. "In order to do that, we need to ensure that middle class jobs pay middle class wages."

The rule change is authorized under New Deal-era legislation called the Fair Labor Standards Act. As recently as 1975, more than 60 percent of salaried workers were eligible for overtime. Inflation and regulatory changes under the George W. Bush Administration eroded that protection, and today, only about 7 percent of salaried workers receive time and a half when they work extra hours. Managers at many retail stores and fast food restaurants making as little as $24,000 have not been eligible for overtime, even when they work 60 or 70 hours a week.