March 24 (Bloomberg) -- Senator Arlen Specter, a Pennsylvania Republican, said he opposes the “card-check” union organizing measure, dealing a setback to U.S. labor’s top legislative goal.

Specter said that he is likely to be the “decisive vote,” to block the Democratic-backed bill that would make it easier to form unions.

“The problem with the recession makes this a particularly bad time,” Specter said on the Senate floor today. Employers fear the measure “will result in further job losses,” he said.

Wal-Mart Stores Inc., Starbucks Corp., and Burger King Holdings Inc. are among companies that oppose the bill, which is backed by most Senate Democrats and President Barack Obama.

Senate Majority Leader Harry Reid, a Nevada Democrat, held out hope for the measure, saying Specter “is not the only Republican who has indicated a willingness” to support it. Specter’s decision may doom the proposal, said William B. Gould, a former head of the National Labor Relations Board.

“This is going to make it extremely difficult to get this bill passed,” Gould said.

Specter said that all Democrats are likely to back moving to a final vote, while all Republicans will oppose it, leaving him with the deciding vote. Specter was the only Republican who voted to cut off the debate when the bill was considered in 2007.

Previous Congress

In the previous Congress the measure fell nine votes short of the 60 needed to move to a final decision. Democrats gained seats in the 2008 election and now control the U.S. Senate 58 to 41.

The bill would let workers chose to form a union when a majority of company employees sign a card requesting one, rather than permitting their employer to require a secret-ballot election run by the National Labor Relations Board.

The legislation, formally called the Employee Free Choice Act, would amend the National Labor Relations Act of 1935, the Depression-era law that helped build the modern labor union movement in the U.S.

Senator Tom Harkin, an Iowa Democrat who introduced the bill on March 10, said he was “disappointed” with Specter’s decision. “The bill should be brought up with the opportunity for amendment,” Harkin said. “I will continue to work with Senator Specter to move ahead on the bill.”

Wal-Mart spokesman David Tovar said Specter “‘came to the right decision.”

To contact the reporter on this story: Holly Rosenkrantz in Washington at hrosenkrantz@bloomberg.net

Last Updated: March 24, 2009 16:55 EDT