Washington ? Maryland’s bold new law requiring Wal-Mart and other large companies to increase health care coverage of their workers has given new life to supporters trying to pass similar legislation nationwide.

The state’s Legislature on Thursday passed a law that directs firms with more than 10,000 employees to spend at least 8 percent of their payrolls on employee health benefits. The law targeted Wal-Mart, the world’s largest retailer, whose low pay and scant benefits have drawn widespread criticism.

In at least 30 other states, plans are under way to draft and introduce similar “fair share” laws. A proposal in Rhode Island would require companies with 1,000 or more employees to spend 8 percent of their payrolls on health benefits. A bill in Washington state would require companies of 5,000 or more to spend 9 percent of payroll on employee health care.

In each state proposal, affected companies that don’t meet the payment threshold would have to pay the difference into a state fund to assist the uninsured.

Maryland’s law overcame fierce opposition from Wal-Mart and a veto by Republican Gov. Bob Ehrlich.

To rein in state Medicaid costs for the uninsured, which now rival spending for education, supporters say it’s important that large companies provide adequate coverage for workers and their families.

The percentage of businesses that offer health insurance has declined for five straight years, according to a 2005 report by the Kaiser Family Foundation. The cost of health insurance premiums has gone up 73 percent, the Kaiser study found.

But groups such as the state and national chambers of commerce and the National Federation of Independent Business have strongly opposed “fair share” measures, saying they could scare new jobs away and cause the number of existing jobs to dwindle if cash-strapped employers can’t afford the mandated coverage.

Fair share laws also don’t address the problem of the uninsured and rising health care costs, said Helen Darling, president of the Washington Business Group on Health, which represents the health care interests of more than 200 large employers that provide health coverage for more than 51 million people.

“We’re very concerned about states taking steps like this, which really is a mandate on businesses,” Darling said.