Delivering the GOP's weekly media address, Collins struck out at the Affordable Care Act's definition of a full-time worker as someone who works 30 hours a week, CNN reported.
Such a provision has "perverse incentives" for employers to cut workers' hours to avoid providing them with health insurance, she said.
The Obama administration has delayed implementation of the provision until 2015 to give employers more time to prepare for the change. Employers who don't provide insurance for their full-time workers would face fines.
Collins called the fines "a real threat to employers who want to add jobs."
In anticipation of the law, the "overwhelming majority" of workers hired this year are part time, she said.
Collins introduced the "Forty Hours is Full Time Act" in April that would increase the number of hours employees would have to work each week to be considered full time.
She quoted labor leaders as recently telling the president the 30-hours-a-week provision would "destroy the foundation of the 40-hour work week that is the backbone of the American middle class."
"Of course, fixing this one flaw won't solve the countless problems caused by Obamacare," she said. "But it would help ensure that millions of American workers do not have their hours, and their paychecks, reduced."