Hoping to drive a wedge into the ruling coalition, four opposition parties submitted a bill Wednesday to freeze a planned 50 percent increase in the fees salaried workers pay for outpatient medical care.

Lawmakers of the Democratic Party of Japan, the Japanese Communist Party, the Liberal Party and the Social Democratic Party submitted the bill aimed at preserving the current health insurance law to the House of Representatives.

The ruling coalition hopes to increase the share of outpatient medical costs that workers must pay to 30 percent from 20 percent beginning April 1.