COLUMBIA -- Bidding to maintain South Carolina's anti-union status, Republican legislators want to exempt businesses from a proposed federal rule that they notify workers of their rights to unionize.

The so-called "employer free speech act," co-sponsored by 63 House members, is the latest show of lawmakers' disdain for unions in a state that markets itself as anti-union. A House panel advanced the bill Wednesday to the full Judiciary Committee.

"South Carolina has long prided itself on being a right-to-work state," said the main sponsor, Rep. Alan Clemmons, R-Myrtle Beach. "I have a visceral objection to employers being forced to espouse rhetoric they don't support."

He also said the anti-union status is a key development tool in South Carolina, which recently has lured such big projects as a Boeing Inc. jetliner plant and an Amazon warehouse while struggling with an unemployment rate above 10 percent.

South Carolina's conservative leadership has repeatedly battled the federal government under President Barack Obama's administration, most prominently on the federal health care law.

Last week, Republicans in the House pushed through a measure meant to eventually allow states to repeal federal mandates, through a long and unlikely path involving a Constitutional Convention.

South Carolina, like many other states, bars government employees from collective bargaining. Just 5.4 percent of workers in the state were covered by unions in 2009, a tie with Virginia. North Carolina ranked last with 4.4 percent, according to data from the federal Census.

Opponents of unions bristle at the federal proposal put forward by the National Labor Relations Board after it gained its first Democratic majority in a decade through appointments by President Barack Obama.

The NRLB proposal would mandate that businesses post, in color and at least 11-by-17 inches in size, the 1935 federal law that guarantees employees' rights to bargain collectively, distribute union literature and engage in other union activities without reprisal. Other agencies require similar postings on minimum wage, civil rights, overtime, and other workforce-protection laws.