The US Senate is heading for a crucial vote today on President George W. Bush's plan to overhaul immigration laws after Senate leaders battled to fend off efforts by opponents to derail the bill.
The fate of the bill is in doubt as the Senate prepared to decide today whether to bring debate to a close and move toward a final vote on the controversial legislation that would legalise millions of unlawful immigrants.
Supporters need 60 votes in the 100-member Senate to push the bill toward a final vote, and they expect today's tally to be close.
The bill's backers yesterday were able to kill a number of amendments they said would have undermined the compromise crafted during months of talks by a group of Democrats and Republicans and the White House.
But they were unable to block a key amendment that would change worker identification requirements, casting doubt on the final outcome of the bill.
Mr Bush has sought an overhaul of US immigration laws for years, and this bill may be his last chance for a significant domestic legislative victory before leaving office when his second term ends in a year and a half.
But the president has encountered opposition from many fellow Republicans who say it would do little to stem the flow of illegal immigration into the United States.
The bill ties tough border-security and workplace-enforcement measures to a plan to legalise an estimated 12 million illegal immigrants and create a temporary worker programme sought by business groups.
If supporters fail today to win the 60 votes needed to advance legislation in the Senate, lawmakers are unlikely to return to comprehensive immigration reform before next year's presidential election.