Liberal Democrats are looking to beef up benefits for part-time workers who face hurdles in finding full-time gigs in a sluggish economy.

Rep. Jan Schakowsky of Illinois, vice chairwoman of the Democratic Steering and Outreach Committee, has been promoting a “bill of rights” for part-time workers that would mandate extending benefits similar to those provided to full-time workers. It would provide most part-time workers with employer-mandated coverage under the health care law and increase access to family and medical leave and to 401(k) plans.

Although the measure faces strong GOP opposition, Schakowsky says she believes it will raise awareness of the needs of part-time workers. She says her proposal would be one option for a Democratic motion to recommit if House Republicans move in coming weeks on a proposal to raise the workweek threshold from 30 to 40 hours for workers to qualify for employer-mandated coverage under the health care law starting in 2015.

The Schakowsky bill has 17 Democratic co-sponsors including several senior members of the Congressional Progressive Caucus, such as Barbara Lee of California and Louise M. Slaughter of New York. Supporters say they are trying to build on the work of state and local governments that are broadening benefit mandates for part-time workers.

For example, the city of San Francisco has required employers to provide most part-time workers with paid sick leave since 2006, and health care benefits since 2008. Hawaii has required businesses to provide health care coverage for employees who work at least 20 hours per week since 1974.

Republicans warn that new benefit mandates for part-time workers would force employers to find other ways to cut costs, such as simply cutting jobs. Sen. Richard M. Burr of North Carolina says such changes might have unintended effects, like enticing some workers to forgo full-time jobs if they can get similar benefits for part-time work. “It would be a big disincentive to work,” he said.

But Schakowsky said she doubted her proposal would have a big impact on hiring or reducing the number of full-time workers. She said many employers would still need to retain full staffing to keep operating.

“To the extent that it would encourage them to hire more full-time workers, that would be a good outcome,” Schakowsky said.