WASHINGTON — A controversial immigration bill survived a key Senate vote Tuesday but still could be derailed by dozens of thorny amendments that threaten to upset the fragile compromise.
With President Bush aggressively lobbying for its passage, the Senate voted 64-35 — four more than were needed — to reopen debate on the legislation. But final approval was uncertain given the level of opposition to the bill, which would harden the nation's borders and provide a chance at legal residency for millions of undocumented immigrants. Several senators said they voted to start debate but reserved judgment on the bill's ultimate merits.
Still, backers said revival of the bill — which was pulled from the floor earlier this month after supporters failed to secure 60 votes on a procedural vote — was cause for celebration.
"I'm very concerned about the passage of the bill, but I'm very elated with this vote," said Sen. Mel Martinez, R-Fla., a chief champion of the legislation.
"The important thing is we have a path forward," said Homeland Security Secretary Michael Chertoff. "Two weeks ago, people were saying this bill was dead, and here we are getting ready to move on to a debate."
One sign of the challenge ahead: debate was delayed late Tuesday as opponents pulled a parliamentary maneuver, forcing the Senate clerk to read aloud the entire text of 26 amendments. They relented after an hour, but their point was made.
Bush has made the legislation his top domestic priority. Tuesday's vote came after he renewed his call, asking the Senate to pass what he called a "careful compromise."
Bush aides said they're optimistic about the once moribund bill's chance at clearing the Senate this week, and Bush noted that "when successful in the Senate, we'll be reconvening to figure out how to get the bill out of the House."
"I view this as an historic opportunity for Congress to act," he told business leaders meeting near the White House.
But the bill's prospects in the House are even hazier. House Majority Leader Steny Hoyer of Maryland and other Democrats believe there should be immigration legislation, but Hoyer declined Tuesday to predict when or if the House would begin debate on a measure.
Crafted by a bipartisan group of senators and two Bush Cabinet secretaries, the Senate bill seeks to legalize millions of undocumented immigrants, create a temporary guest-worker program, toughen security along the U.S. borders with Mexico and Canada, and crack down on employers who hire illegal workers.
But along the way the bill has picked up vocal detractors from the right — who considers legalization as amnesty for lawbreakers — and from some Democrats who say the bill's emphasis on skills-based immigration could be harmful to families. Both sides have proposed changes that could sink the legislation.
Advocacy groups Tuesday pledged renewed efforts to ramp up their efforts.
"People are really worked up about this and they're willing to make the calls," said Caroline Espinosa, a spokeswoman with Numbers USA, which wants to cap immigration. "The Senate will be feeling that pressure."
Bush acknowledged Tuesday that not everyone is happy with the Senate bill.
"In a good piece of legislation like this, and a difficult piece of legislation like this, one side doesn't get everything they want," Bush said.
One major point of contention: a bid to lure more Republican support by requiring the head of an illegal immigrant household to leave the country in order to secure a Z visa, which would allow them to stay in the country. It also would call for deporting and permanently barring those who overstay their visas.
Negotiators on the legislation were looking to ward off an amendment by Sen. Kay Bailey Hutchison, R-Texas, that would require all undocumented work-eligible adults to return to their home countries at least temporarily. But bill supporters acknowledged that even the restricted "touch back" provision proposed by the bill's negotiators was likely to turn off some Democrats.
New Jersey Democratic Sen. Bob Menendez, who voted to proceed, warned late Tuesday that he'll peel off if the bill continued to veer "to the far right." He has proposed an amendment that would give more emphasis to immigrants with family ties in the United States.
"I think it's important to give this bill another chance on the Senate floor, but I remain seriously concerned by the direction the amendment process is taking," Menendez said. "The tilt and tenor of amendments written by the Republican grand bargainers are becoming increasingly onerous and impractical."
And Sen. Jim Webb, D-Va., who voted to revive the bill, cautioned that he's not necessarily in the "yes" camp. Webb has proposed an amendment to limit legalization to immigrants who have been in the United States for more than four years.
"If my amendment is heard and succeeds, I'll support the bill," Webb said. "If not, I won't, unless there's something similar in there."
Martinez called the attempts to balance the bill amid its many detractors "one of the dilemmas of this bill."
"As we try to do things that are hopefully going to attract more people to the bill, there are others who aren't attracted," Martinez said.
He called requiring immigrants to return home a "confidence builder, something to show people that we're serious about the enforcement aspect."
Also controversial is a business-backed measure that would reduce the number of workers that employers would have to verify as legal.
Business groups support the measure backed by Sens. Charles Grassley, R-Iowa, Barack Obama, D-Ill., and Max Baucus, D-Mont., but the White House opposes it, calling it "a serious step backwards in our enforcement effort."
(James Rosen and Margaret Talev contributed to this report.)