Madison -- Wisconsin communities could lose $70 million or more in federal aid for transit systems under a bill quickly moving through the state Legislature, opponents of the bill are warning.

The measure by Gov. Scott Walker would strip most union rights away from most public employees. That could put in danger federal aid for buses because U.S. law requires that collective bargaining rights remain in place to get federal funds, according to the U.S. Department of Labor.

"It’s a $70 million problem," said Assembly Minority Leader Peter Barca (D-Kenosha). "That’s not small change."

Walker spokesman Cullen Werwie denied the bill would affect federal transit funding.

"The budget repair bill meets all of the federal requirements to continue to receive federal transportation aid," Werwie said in a statement.

But according to the Department of Labor’s website, the Federal Transit Act "requires the continuation of any collective bargaining rights that were in place when the employer started receiving federal funds."

Werwie declined to say if an amendment was needed to the bill now pending in the Legislature. Andrew Welhouse, a spokesman for Senate Majority Leader Scott Fitzgerald (R-Juneau) said he did not know if lawmakers would amend the bill to address the federal transit funding.

Walker’s fellow Republicans who control the Legislature plan to pass the bill this week. The bill would require most local, school and state employees to pay at least 12% of their health care costs and half their pension costs, which would amount to 5.8% of pay for most state employees. Police, firefighters and state troopers are exempt from the changes.

The bill also strips away most union rights for public workers. Raises would be limited to the rate of inflation unless higher raises were approved in a referendum, and unions could negotiate over wages only. Unions would have to hold annual elections to keep their organizations intact and the state would no longer collect union dues from paychecks.

By changing the bargaining laws for transit workers, federal money could be at risk. The Department of Labor would ultimately make the call.

Lawmakers say they have not yet heard from federal authorities, but hope to before the bill passes.

The Legislature’s budget office expects the state to receive $70 million to $75 million in transit aid this year.

One question is how communities like Milwaukee County would be treated. Milwaukee County and some other areas have transit systems that are run by private contractors. Gary Goyke, the lobbyist for the Wisconsin Urban and Rural Transit Association, said he believed such systems would be in danger of losing funding, just as those that are run directly by public entities would be.

Democrats say the transit problem is a sign Republicans need to slow their consideration of the bill.

"The last thing we need, especially in areas like mine, is a decline in things like transit funding," said Rep. Gordon Hintz (D-Oshkosh).

Walker is calling for the bill to be quickly approved because the benefits cuts and other changes will help the state’s bottom line as it tries to fix a shortfall of more than $3 billion through mid-2013.