The US Senate dealt a fatal blow on Thursday to President George W Bush's overhaul of immigration policy -- an emotional issue that has divided Americans in the run-up to next year's presidential election.
Dashing the hopes of millions of immigrants seeking legal status and exposing a deep lack of support among Bush's own Republicans, the bill fell 14 votes short of the 60 needed in the 100-member Senate to advance toward a final vote.
A crestfallen Bush conceded defeat and said he was moving on to other issues such as balancing the federal budget when it became clear the immigration legislation would not be revived during the final 18 months of his two-term presidency.
"A lot of us worked hard to see if we couldn't find common ground. It didn't work," said Bush, who has seen his approval ratings slump to about 30 per cent amid anger over the Iraq war and a generally negative public mood.
The bill tied tough border security and workplace enforcement measures to a plan to legalise an estimated 12 million illegal immigrants, most from Latin America, and to create a temporary worker program sought by business groups.
It also would have created a merit-based system for future immigrants, something conservative Republicans sought.
The bill was the fruit of months of negotiations by a group of Republican and Democratic senators and the White House.
But the president was unable to overcome fierce opposition from fellow Republicans who said it was an amnesty that rewarded illegal immigrants. A majority of Republicans in the House of Representatives also opposed the Senate bill.
Supporters were dismayed and said it was unlikely Congress would tackle comprehensive immigration reform before the presidential election in November 2008
"No one benefits now," said Rosa Rosales, the national president of the League of United Latin American Citizens. "It's very disappointing."
Analysts say public understanding of the issue was clouded by reports by partisan think tanks and lobbyists as well as by accounts from "advocacy" journalists and talk-show hosts and the free-wheeling exchanges of Internet blogs.
Many opponents said illegal immigrants took jobs from US workers, while employers from Arizona to Texas shot back that thousands of farm, construction and restaurant jobs were going begging through a lack of takers.
Mexican President Felipe Calderon said the US Senate made a "great mistake" by defeating Bush's measure.
"The US economy cannot keep going without migrant labor," Calderon said.
Bush has sought to overhaul US immigration laws for years and the bill was seen as his last chance for a major domestic legislative victory before leaving office in January 2009.
The United States is building a 700-mile (1,100-km) fence along parts of its 2,000-mile (3,200-km) border with Mexico and boosting security by adding trucks with infrared cameras, sensors that detect footsteps and surveillance drones.
But even the bill's promise of an extra $4.4 billion for more border enforcement did not quell Republican opposition.
The bill was also opposed by some labor unions, which said its temporary worker program would have created an underclass of cheap laborers. Immigrant groups opposed measures in the bill that limited migration on the basis of family ties.
The legislation failed to garner even a simple majority.
Only 33 Democrats, 12 Republicans and one independent voted to advance the bill, while 15 Democrats joined 37 Republicans and one independent to block it.
Five of the six senators running for president voted in favor of the overhaul: Republican John McCain and Democrats Hillary Clinton, Barack Obama, Christopher Dodd and Joe Biden.
In Los Angeles, a high-profile supporter of immigration reform, Roman Catholic Cardinal Roger Mahony, said the current system "will continue to permit the exploitation of workers, the separation of families, and will handicap efforts to secure our nation's borders."
A Pew Research Center survey found most Americans favored at least one of the proposal's major objectives, but the overall bill drew a negative reaction. A Gallup Poll put opposition at 60 per cent among those who paid close attention to the bill.
For Juan Carlos Esquivel, a day laborer from Mexico City with a wife and three children, the defeat made no sense.
"There's work to be done, we want to do it, and now we can't," he said, standing in the shade against the searing heat in Phoenix. "So how can that be a victory?"