WASHINGTON — Senate Republicans yesterday blocked a bill that would allow labor unions to organize workplaces without a secret ballot election.

Democrats were unable to get the 60 votes needed to force consideration of the Employee Free Choice Act, ending organized labor’s chance to win its top legislative priority from Congress.

The final vote was 51–48.

The outcome was not a surprise, with the minority leader, Senator McConnell, a Republican of Kentucky, saying for months that he would stop the legislation in the Senate. The White House also made clear that if the bill passed Congress it would be vetoed.

The House passed the bill in March. Democrats and labor unions pressed for a vote in the Senate in hopes of rallying their voters in the 2008 elections, where they hope to win the White House and increase their majorities in the House and Senate.

“We will keep coming back year after year after year,” Senator Brown, a Democrat of Ohio, said.

The GOP also plans to use the vote for election-year campaigning, with corporations and businesses being the top opponents to the legislation. The National Republican Senatorial Committee sent out a fund-raising video last week asking people to contribute in order to help stop the Employee Free Choice Act.

“Republicans will remind our constituents about the fact that Democrats proposed to strip workers of their voting rights,” Mr. McConnell said. The legislation was a litmus test vote for organized labor and businesses, strong supporters of Democrats and Republicans respectively.

Business associations, like the U.S. Chamber of Commerce, also plan to grade lawmakers based on their vote. “The Chamber will include votes on, or in relation to, this issue in our annual ‘How They Voted’ scorecard,” warned R. Bruce Josten, the top U.S. Chamber of Commerce lobbyist, in a letter to Congress.

The bill would require employers to recognize unions after being presented union cards signed by a majority of eligible workers on their payrolls. Under current labor law, a company can demand a secret-ballot election supervised by the federal government after being presented the union cards.

The bill’s proponents say years of Republican control of the White House and Congress have given corporations and businesses the upper hand when it comes to union elections. Obstacles to organizing are a major reason union membership has dropped from 20% of wage and salary workers in 1983 to 12% in 2006, they say.

Unions complain that employers have greater access to workers during secret ballot campaigns and claim that corporate threats, intimidation, and eventual firings have become common for union activists. By dragging out the election process, companies often succeed in wearing down union enthusiasm, they add.