WASHINGTON (CNN) -- The battle over immigration reform moves Tuesday to the full Senate, a day after a GOP-led Senate committee passed sweeping legislation that sets up a contentious showdown with Republicans demanding a harder line.

Controversial provisions in the Senate Judiciary Committee's election-year bill would create a guest-worker program and give illegal immigrants the chance to work toward legal status without first returning home.

Highlighting the divisions within GOP ranks over immigration, four of the committee's 10 Republicans voted in favor of the bill, which passed 12-6 with support from the panel's eight Democrats.

The full Senate begins debating immigration Tuesday, and it is unclear whether the committee's version will have enough support to survive intact. A procedural vote Tuesday may give some indication of its chances.

Committee Chairman Arlen Specter, a Pennsylvania Republican, told the Senate after the panel vote that he expected "considerable controversy when the bill reaches the Senate floor."

"It is a very emotional issue; it is a very contentious issue," he said. (Watch a new citizen who does work at the White House -- 2:25)

The biggest bone of contention is likely to be the legalization process for undocumented immigrants already in the country -- a controversial idea denounced as "amnesty" by its critics and opposed by President Bush.

Meanwhile, as the debate swirled in Washington, immigration supporters rallied Monday in cities around the country -- including Los Angeles, California; Dallas and Houston in Texas; Boston, Massachusetts; Detroit, Michigan; and Washington, D.C. -- to denounce proposed restrictions they view as fundamentally un-American. (Full story)

"It's thanks to us that this country is what it is to this day, and what [it] will be for the future," said Ardaya Barron, a native Bolivian who joined the protest in Washington, where demonstrators chanted, "We are Americans ... We are American."

In Los Angeles, an estimated 22,000 Latino high school and middle school students -- many waving American, Mexican, Venezuelan, Salvadoran and other flags -- skipped class and staged impromptu protests across the city, one of which briefly shut down a freeway.

Mayor Antonio Villaraigosa, the city's first Latino mayor in more than a century, met with student leaders and urged them to return to class.

"It was nothing short of amazing how eloquent they were," Villaraigosa said. But he added: "We're very clear these young people need to go back to school." (Watch mayor talk about 'demonizing' 11 million people -- 4:43)

'Compromise and tough choices'
The committee's vote was a partial victory for Bush, who supports a guest-worker program to fill jobs for which no American workers are available. After the vote, White House spokesman Scott McClellan praised the fact that the Senate was "moving forward" on legislation.

"The President believes comprehensive reform is needed if we are going to have a rational, orderly and secure immigration system," McClellan said, noting that the president has "outlined some clear principles" on immigration reform.

"It is a difficult issue that will require compromise and tough choices, but the important thing at this point is that the process is moving forward," he said.

While McClellan did not directly address the issue of amnesty for undocumented immigrants, Bush said again Monday that he does not support the idea.

"Granting amnesty would be unfair, because it would allow those who break the law to jump ahead ... of people who play by the rules and have waited in line for citizenship," Bush said earlier in the day at a swearing-in ceremony for new citizens in Washington. (Watch Bush aim border controls on 'criminals, drug dealers and terrorists' -- 5:54)

Delicate political dance
The immigration bill presents a delicate political dance for Bush. His guest-worker program has support in the business community, and he has successfully courted Latino support during his presidency.

But he also must deal with an outspoken segment of his conservative base demanding restrictions on immigration.

That sentiment was on display in December, when the Republican-controlled House passed an immigration bill without a guest-worker program or a process for legalization for undocumented immigrants.

The House bill -- which has drawn fierce opposition from Latino groups -- also called for building 700 miles of security fence along the U.S.-Mexico border, and would make illegal immigration a felony.

House Judiciary Committee Chairman James Sensenbrenner, who sponsored the House bill, said Monday that the measure coming out of the Senate committee would let illegal immigrants "jump to the head of the line" over people waiting for legal residency.

The Wisconsin Republican warned that without changes, another 20 million illegal immigrants will enter the United States in the next 10 years.

"They'll flood our schools. Our health-care system will collapse, and our social service system will end up being overtaxed," Sensenbrenner told CNN. "We've got to get control of our borders, because if we don't, we're going to see our economy collapse."

'Legalization' at center of debate
For weeks, the Judiciary Committee had wrestled over an immigration reform bill.

Expressing frustration at the pace, Senate Majority Leader Bill Frist, a Tennessee Republican, scheduled a debate on the issue starting Tuesday, telling committee members that he would bring his own bill to the floor if they could not come up with a proposal. (A look at the competing bills)

However, the measure adopted by the committee differs significantly from Frist's bill, which did not contain a guest-worker program or a process under which people in the country illegally could work toward legal status.

By a 12-5 margin, the committee accepted an amendment from Sen. Ted Kennedy, a Massachusetts Democrat -- and backed by Arizona Republican Sen. John McCain -- that would create a legalization process.

In order to gain permanent residency, illegal immigrants would have to wait six years, pay $2,000 in fines and any back taxes, undergo a background check and learn English.

"I believe we have a bill which is not justifiably categorized as amnesty," said Specter. He rejected the option of forcing illegal immigrants to return home before working toward legal status as "unrealistic."

The four Republicans on the committee who supported the immigration bill were Specter and Sens. Mike DeWine of Ohio, Sam Brownback of Kansas and Lindsey Graham of South Carolina. Brownback has been mentioned as a potential 2008 presidential candidate.

Sen. John Cornyn of Texas, a border state Republican on the committee who supports a guest-worker program, voted no, saying he will oppose any measure that would offer a legalization process.

"We made a mistake in 1986 by saying that we would grant amnesty to 3 million people," Cornyn said, referring to Congress' last stab at comprehensive immigration reform. "Now we have 12 million here today living in the shadows."

"Our intention is not to repeat that mistake, but to come up with a different solution that learns from that mistake."

During its deliberations Monday, the committee adopted two additional Democratic amendments to soften some of the hard-line immigration restrictions in the House bill.

One, sponsored by Sen. d!ck Durbin of Illinois, would allow church and charitable groups, as well as individuals, to provide assistance to undocumented immigrants without facing criminal charges. The House bill made providing such aid a felony.

The committee also approved an amendment by California Sen. Dianne Feinstein of California that would allow 1.5 million undocumented agricultural workers to stay in the United States for up to five years.

It doesn't matter anymore that it used to be there land, why doesn't the US give stolen land back to the Native Americans? This is the US now.

Jasel do you even think it would be possible to deport 12 million people?

Even if you do, a lot of them are just gonna come back if you don't have a big fu-king wall.

A lot of illegals have kids that were born here so you're gonna have to split up families and $hit. Mass deportations is just gonna complicate $hit to a level I don't think anyone wants to go. The goverment probably shoulda addressed this issue a long time ago.

with the over crowded prison system here in cali I dont know how making it a felony is gonna help. also if you get caught three times thats life in the pen . Expect taxes to get raised

What I heard is Right now California cant build prisons fast enough to house all the convicts is has already. That total sounds about right.

Err...why not deportation?

California, Texas, Arizona, Nevada, @ New Mexico are now Mexico..

Bush was in Cancun for a meeting with Mexican president Vicente Fox on the immigration issues.

Apparently, the unemployment rate in Mexico is at 40% and president Fox would prefer to send the poor population over to the US, instead of dealing with the problem himself. After all, he is Mexico's president. He even refuses to crack down on the movement of illegal immigrants, stating that it was against the Mexican constitution. What a pathetic excuse for a Mexican president, whose government is so corrupted by the drug cartel and he refuses to take responsibility for his people. So it looks like there won't be any cooperation from Mexico. It's now up to the US, as a sovereign nation, to implement policies to protect its border.

Hopefully, that will be soon because hospitals in California are being shut down because the emergency room could not afford treating these undocumented uninsured patients. Schools are overcrowded with Spanish speaking students and teachers are dropping like flies. Not to mention the overcrowded prison system and the MS-13 Salvadorean gang spreading across the US.

So what do you propose the US to do about it?