By Nick Carey

DETROIT, March 1 (Reuters) - A December sit-in at a closed factory in Chicago made national headlines for the workers at Republic Windows & Doors when they won severance and health care from the shuttered company's lenders.

Among those speaking in support of their cause was the new U.S. President-elect Barack Obama, a former Chicago community organizer. Now the workers have taken to the road to rouse other blue-collar workers to organize for a bigger battle.

As U.S. unions and business groups gear up for an epic fight over the Employee Free Choice Act (EFCA), unions claim the refusal of the Republic workers to back down can inspire the best chance in decades of winning more rights for other workers.

The EFCA -- which would allow workers to form unions by simply signing a card rather than having a secret vote -- was approved by the U.S. House of Representatives in March 2007. But Republican opposition prevented it from coming up for a vote in the U.S. Senate.

The law -- sponsored by many lawmakers, including Obama -- is anathema to corporate America. It will face a stiff filibuster test in the U.S. Senate, where Democrats need at least 60 votes to bring it to Obama's desk for signing.

That's the barrier Republic workers are attacking.

"The workers at Republic Windows stood up by sitting down and demanding justice," Bob Kingsley, director of organization at the United Electrical, Radio and Machine Workers of America (UE), said at a recent rally in a packed union hall in Detroit -- and got a standing ovation.

More than 400 people -- white, black, Hispanic -- showed up to hear Kingsley, whose union members worked at Republic Windows. Detroit was one of 15 cities Kingsley has visited as part of a tour to exhort workers to organize for rights.