Differing predictions

for more teeth, different standards, and meaningful triggers.”

The bill requires a 90 percent effectiveness rate for security along the entire southwestern border and prevents undocumented immigrants who are granted provisional legal status from receiving any federal means-tested public benefits such as welfare or Medicaid.

But conservative critics don’t like the fact that undocumented immigrants would gain temporary legal status before the border requirements have to be met.

And some want to deny newly legalized immigrants any federal, state or local aid or tax breaks even when they earn green cards and become permanent legal residents.

“This is a tricky period,” said Frank Sharry, executive director of America’s Voice, a national organization that champions comprehensive immigration reform. “If they (the Gang of Eight senators) go too far in trying to placate Republicans and undermine the parts of the bill that brought the progressive coalition to the table, they could lose us.”

Immigrant-rights leaders say they don’t want border-security requirements that are so rigid they are impossible to meet.

If those requirements are tied to citizenship, then millions of people would remain here with no hope of ever becoming citizens or even legal permanent residents, immigrant-rights leaders say.

“We already have a path to legality in this bill that is quite narrow, quite hard and quite long,” said Clarissa Martinez, director of civic engagement and immigration at the National Council of La Raza. “We are going to be vigilant about opposing any amendments that intend to make that path even harder because that might make citizenship unattainable.”

Cutting off all federal aid to newly legalized citizens could have unintended consequences such as denying them disaster aid in the event of a powerful tornado or hurricane, Martinez said.

“We just went through this horrific tornado in Oklahoma,” Martinez said. “What happens if your house has been leveled, your job has been obliterated, one of your family members ends up in the hospital as the result of a tragic event? People need to be able to survive while they work and wait to become citizens.”

Groups that oppose increased immigration say there is no way to salvage the bill and that conservatives should work to defeat it rather than amend it.

“If the bill were to be essentially torn up and replaced with one that required E-Verify and border security and an entry-exit visa system before legalization, it would be less bad, but the Gang of Eight couldn’t support that,” said Mark Krikorian, executive director of the Center for Immigration Studies.

The center opposes increased immigration and is a strong supporter of mandatory E-Verify, the electronic federal database that allows employers to check if new hires are eligible to work in the United States. Arizona law already requires employers to use the system.

Krikorian said it’s possible that liberals could end up killing the bill if they offer a controversial amendment to allow gay Americans to bring in their foreign partners on family reunification visas.

‘‘ The final bill won’t be exactly what passed out of the committee.”

Senate Judiciary Committee chairman

“I could see Republicans voting for it as a poison-pill kind of thing,” he said. “But I doubt that (Senate Majority Leader) Harry Reid will let it go that far. I think the Democrats have essentially told the gay-rights groups that they need to hold off for now.”

Liberal Democrats also are expected to offer amendments that would continue to allow siblings and adult married children to immigrate to the United States on family-reunification visas.

Under the current bill, those family categories would be eliminated to allow for more employment-based visas sought by businesses and favored by many Republicans.

“What if your only family member is a sibling?” Martinez said. “We’d like to see more flexibility there before we do away with something that is tried and true and replace it with a new system.”

While many Democrats favor changes to help gay couples and reunite all family members, they are not expected to vote against the bill if those amend- ments fail.

“They see the larger goal of passing immigration reform as more important,” Yale-Loehr said.

Jacoby said she doesn’t think the bill will drastically change on the Senate floor, even though she and other business advocates would like to see an increase in the number of visas made available to lower-skilled workers.

She cited the influence of the labor giant AFL-CIO, which negotiated the part of the bill pertaining to lower-skilled worker visas with the U.S. Chamber of Commerce.

“There will be some drama, but I think a lot of it is locked in by the Gang of Eight,” said Jacoby, whose organization is a national coalition of small and medium-size business owners that pushes for immigration reforms to benefit employers. “They have a pretty protective approach, the Gang of Eight does, and they feel that if they change any of the labor stuff, the AFL will bolt, and that basically gives the AFL a trump card.”

The lobbyist for NumbersUSA, which opposes increased immigration, questioned the Gang of Eight’s ability to get the full Senate to approve the bill.

NumbersUSA is running TV ads nationwide saying the legislation would hurt U.S. citizens and legal residents at a time when 20 million Americans are unemployed or underemployed.

“I think the bill is in serious trouble,” said Rosemary Jenks, NumbersUSA’s government-relations director. “I don’t think they have the 60 votes (needed to fend off a conservative filibuster). They are not going to get all 55 Democrats, especially the ones from red states. And I don’t see them getting enough Republicans to make it to 60.”

But supporters of the bill say they don’t see the strong anti-immigrant sentiment that they saw in 2007, when the last serious attempt at reform collapsed amid a public outcry against what was perceived as “amnesty” for immigrants in the country illegally.

“It’s not just that Latino and proimmigration groups are stronger; there’s just nothing going on on the other side,” said Jeff Hauser, an AFL-CIO spokesman. “We’re not seeing the big anti-immigration protests that we saw before.”

Leahy said both sides realize Americans are fed up with the immigration status quo.

“If senators are serious about fixing the problem, this bill will pass,” he said.