WASHINGTON, D.C. -- The U.S. Senate Monday resumed debate on immigration reform, as President Bush addressed the nation about the issue.

The Senate bill - unlike the version that passed the House of Representatives - contains a guest worker provision that would offer illegal immigrants in the United States an opportunity to earn legal status and the possibility of eventual citizenship.

Senate Majority Leader Bill Frist, a Tennessee Republican, predicts the Senate will vote on the bill before the Memorial Day recess at the end of the month.

"It is an important bill," said Bill Frist. "It is an important bill to our national security, it is an important bill to our values, to our economy, and to our safety."

President Bush supports a guest worker program, although many conservatives who make up the base of his Republican Party do not. They say the proposal would reward those who entered the country illegally - an argument supporters reject.

Senator John Cornyn, a Texas Republican, is one who opposes the idea:

"Some say it is not really amnesty," said John Cornyn. "It is earned legalization. Well, whatever it is, it looks very similar, if not its identical twin."

But the Senate's top Democrat, Senator Harry Reid of Nevada, says any immigration reform must address the 11 to 12 million illegal immigrants in the United States:

"The whole point of what we are doing is to deal with this population that is here under the table, for lack of a better description," said Harry Reid. "They are here. They came here illegally."

Once the Senate acts on its bill, which also calls for efforts to boost border security, congressional negotiators will have to reconcile the measure with the House-passed legislation.

Although many House Republicans are strongly opposed to the Senate guest worker provision, one Senate Republican, Arlen Specter of Pennsylvania, believes compromise is possible:

"With the good faith which I know will be present by both bodies, I believe we can craft under our bicameral system a legislative package in conference which will be acceptable to both the House and the Senate," said Arlen Specter.

Senators resumed debate on the bill after Senate leaders last week reached a compromise on some technical issues that had stalled the legislation for weeks.