Republicans will soon take up a measure that would change Obamacare’s definition of full-time work from 30 hours to the traditional official mark of 40 hours per week. The distinction is an important one. As matters now stand, employers will face fines for failing to insure workers who work as few as 30 hours per week.

This is causing many part-time employees — especially waiters and part-time employees of public school districts and colleges — to lose hours and thus lose wages. It might also be preventing the U.S. job market from returning to its previous balance between part-time work (which is now more common) and full-time work (which is now more scarce).