WASHINGTON (CNN) - A controversial bill designed to boost the ranks of America's unionized workers was dealt a potentially fatal blow Tuesday as a key moderate Republican senator announced his intention to oppose it.
Pennsylvania Sen. Arlen Specter, a five-term legislator from a state with a historically strong union movement, said he plans to oppose the Employee Free Choice Act because it threatens to eliminate secret ballots in union elections.
Secret ballots, Specter said in a written statement, are "the cornerstone of how contests are decided in a democratic society."
He added that his decision means that there is likely to be unanimous Republican opposition to the bill. The GOP currently has 41 seats in the Senate - one more than necessary to sustain a filibuster.
If the Democrats cannot find 60 votes in the 100-member chamber to end the filibuster, they cannot bring the bill to a vote.
The controversial act would allow employees to signal support for unionizing by openly signing a card demanding it. If a majority signed, the company involved would have 120 days to negotiate union representation before facing compulsory arbitration.
The bill would also stiffen federal laws barring employers from intimidating or firing workers who try to bring in a union.
The traditional option to vote by secret ballot would still be available.
But critics say the measure - dubbed the "card check" bill by its opponents - would effectively eliminate union elections, removing a fundamental hard-earned right of workers and forcing some workers into unions they don't want to join.
Specter said his decision to oppose the bill was "very emotional" and "a close call" on the merits. He argued that in seeking "more union membership and negotiating leverage, labor has a valid point that they have suffered greatly from outsourcing of jobs to foreign countries and losses in pension and health benefits."
The Employee Free Choice Act is supported by President Barack Obama and the Democratic congressional leadership, but is fiercely opposed by most congressional Republicans and corporate leaders, who fear it will saddle a sagging business community with new burdens at the worst possible time.
Senate Majority Leader Harry Reid, D-Nevada, dismissed Specter's announcement as little more than an effort to undermine potential conservative primary challengers before the veteran GOP senator's expected 2010 re-election bid.
Reid said there are other Republicans besides Specter who may support the bill, though he declined to provide any names.
- CNN's Ted Barrett contributed to this report