After months of debate, the bill cleared the chamber by a 62-36 vote and must now be blended with the House's version.
The Senate legislation would allow illegal immigrants who have lived in the United States for five years or more, about 7 million people, to be granted citizenship if they have remained employed, passed background checks, paid fines and back taxes, and enrolled in English classes.
Illegal immigrants who have lived here two to five years, about 3 million people, would have to leave the country briefly and receive a temporary work visa before returning, as a guest worker. Over time, they would be allowed to apply for permanent residency and ultimately citizenship.
Illegal immigrants who have been here less than two years, about 1 million people, would be required to leave the country altogether. They could apply for the guest worker program but would not be guaranteed acceptance.
The legislation also would require employers to use a new employment verification system that would distinguish between legal and illegal workers. In addition, it would impose stiff fines for violations by employers, create legal-immigrant documents resistant to counterfeiting, increase the number of Border Patrol agents and mandate other enforcement measures.
Conservatives attacked the bill to the end after trying unsuccessfully to pick it apart with amendments.
"This bill will not secure our borders," said Sen. Jeff Sessions, R-Ala., one of the most persistent critics.
But supporters of the bill hailed the bipartisan coalition that fended off attempts to kill it. Enactment of the measure also would be a victory for President Bush, who supports the guest worker program.
The bill may face a difficult time in conference committee, however, where lawmakers will work to merge it with the House version that contains tougher border and enforcement measures.
"The Senate has provisions that go far beyond (the House bill) and I don't underestimate the difficulties of the House and Senate trying to come together," said House Majority Leader John Boehner, an Ohio Republican, according to Reuters.
