As negotiators worked on a compromise to let those who have been here longest remain, Sen. John McCain, R-Ariz., said a majority in the 100-member Senate support his and Massachusetts Democratic Sen. Edward M. Kennedy's proposal to provide green cards to illegal immigrants after they've worked in the U.S. for six years.
But it takes 60 senators to overcome opponents' parliamentary tactics, and McCain said he doesn't have that many votes.
More than 11 million illegal immigrants are believed to be in the United States, and Sen. Mel Martinez, R-Fla., said he and Sen. Chuck Hagel, R-Neb., are pushing a "fallback" plan that would put those who have been here the longest on a track toward citizenship but treat more recent arrivals differently. A similar approach was rejected by the Senate Judiciary Committee last week but it was revived Monday night during a meeting in Majority Leader Bill Frist's office.
About 30 Republican senators huddled for more than an hour Tuesday, but no consensus emerged. President Bush has championed a program that would give illegal immigrants a legal status to work in the United States — but has not specified whether they should have to leave the country at some point.
McCain and Kennedy deny that their proposal is amnesty, saying illegal immigrants would have to pay $2,000 in fines and any back taxes and clear background checks before they could get in line for a green card.
The proposal, dubbed the "roots concept" by Judiciary Committee Chairman Arlen Specter, R-Pa., seemed to have some support from Frist. He told CNN over the weekend that 40 percent of illegal immigrants have been in the country less than five years and "need to be dealt with in a different fashion."
The Senate is in its second week of debate on immigration-border security legislation and there is pressure to complete a bill before Congress recesses on Friday for a two-week holiday.
With a filibuster possible from either side, CBS News correspondent Bob Fuss reports the goal is to find an immigration bill that can gain 60 votes. But that is proving very difficult, and it is possible the Senate will end this long and emotional debate with no bill at all.
A bill approved by the Senate Judiciary Committee — based on a proposal by McCain and Kennedy — would allow illegal immigrants in the United States before Jan. 7, 2004, and who have jobs, to work legally for an additional six years and eventually become citizens.
Both Frist and McCain are considered likely candidates for the 2008 Republican presidential nomination.
A separate bill filed by Frist does not deal with illegal immigrants, but boosts border enforcement and cracks down on employers who hire illegal workers. The House in December passed a bill that would make being in the country illegally a felony.
Opponents consider the Judiciary Committee bill amnesty. Sens. John Cornyn, R-Texas, and Jon Kyl, R-Ariz., would give illegal immigrants up to five years to leave the country, before they can return legally to apply for permanent residence or be guest workers.
Cornyn was not at the meeting at Frist's office, but his spokesman Don Stewart was skeptical of the suggested compromise.
"It's a matter of giving amnesty to 8 million people or giving amnesty to 12 million people. It's still amnesty to millions of people," Stewart said.