Small-business groups are hailing the defeat of a Senate bill on Tuesday that sought to ease the process of organizing unions in the workplace, calling it a victory for workers and employers alike.

The labor-backed bill, which was blocked by Republicans in a 51-48 vote, would have allowed workers to form a union by gathering signed cards from a majority of their co-workers on an employer's payroll, rather than holding a secret ballot. Under Senate rules, the measure required at least 60 votes to proceed.

The legislation, known as the card-check bill, was approved by the House  in March. The White House has since threatened to veto the bill if it passed Congress.

"Card check will always be a major threat to small businesses," Dan Danner, the executive vice president of the National Federation of Independent Business, said in a statement following Tuesday's vote.

"Had this legislation moved forward, it would have left employees vulnerable to inevitable intimidation and misinformation campaigns," he said.

Danner also pledged to continue fighting against the legislation, saying he expects "special-interest money" to bring the bill back up in the future.    

In a letter to Congress last week, the U.S. Chamber of Commerce attacked the card-check system, calling it an "open-ended process" that allows labor groups to keep campaigns going for as long as necessary to win over enough employees.

"These campaigns are designed to pressure employers through demonstrations, false and misleading stories in the news media, and other public expressions to recognize unions as the exclusive bargaining representative of their employees without having to go through an election," the group said.

For their part, labor groups say employers typically intimidate and even fire workers found to be involved in organizing union campaigns. They say a card-check system would merely level the playing field between employers and their workers.

"Unscrupulous employers routinely break the law to keep unions out," said Sen. Ted Kennedy (D-Mass.), who sponsored the bill. "They intimidate workers, harass them, and discriminate against them. They close down whole departments -- or even entire plants -- to avoid negotiating a union contract."

The issue is expected to be revived during the 2008 federal election.