Raising the definition of a full-time workweek from 30 to 40 hours would result in fewer work hours for many employees, Senate Democrats argued at a hearing last week.

Sen. Elizabeth Warren (D-MA), said the sheer volume of 40-hour-per-week workers makes them a prime target for lesser workweeks so that employers can escape Affordable Care Act coverage dictates. Democrats cited Congressional Budget Office projection that said as many as 1 million workers could lose work-based health insurance if the hourly threshold were raised.

Republicans have consistently attacked the 30-hour workweek as problematic. They did so again at last Thursday’s hearing of the Senate Health, Education, Labor and Pensions (HELP) Committee. Fueling the latest debate is the “Forty Hours is Full Time Act” (S. 30), sponsored by Sen. Susan Collins (R-ME) and Sen. Joe Donnelly (D-IN)

One witness noted that roughly half of all 40-hour workers now receive employer-sponsored health insurance. They would not be likely candidates for work cutbacks, said Douglas Holtz-Eakin, president of the American Action Forum, but the 27% of workers at about the 30-hour-per-week level would be.

An ACA provision mandates that employers with 50 or more workers must provide “affordable” coverage for employees working 30 or more hours per week.

HELP Committee Chairman Lamar Alexander (R-TN) said that employers are already cutting their number of employees because they can’t afford the costs of the insurance mandate.

The House passed a similar bill (H.R. 30) earlier this month. President Obama has threatened to veto any such legislation if it passes both chambers of Congress.