By Caren Bohan and Richard Cowan
WASHINGTON (Reuters) - President Barack Obama on Tuesday embraced a sweeping overhaul of the nation's immigration system put forward by a bipartisan group of senators, saying it was "largely consistent" with his own principles for immigration reform.
The Democratic president, who had said previously that he would submit his own bill if he was not satisfied with the Senate proposal, urged Congress to "quickly move" the bill forward and pledged to do "whatever it takes" to help.
He spoke after meeting with two of the measure's chief sponsors, Senators John McCain, a Republican from Arizona, and Charles Schumer, a Democrat from New York.
Obama's endorsement and the bipartisan support for the bill improves its chances for passage but by no means ensures it.
The four Democrats and four Republicans sponsoring the bill likely face a months-long battle, with the biggest challenge expected in the Republican-led House of Representatives.
Some opposition surfaced Tuesday, even though many House members, including Republican leaders, resolved to stay silent for the day because of the Boston Marathon bombing on Monday.
Republican Representative Lamar Smith of Texas slammed the senators' plan and said it would encourage even more illegal immigration, favor foreign workers and treat illegal immigrants better than those who have played by the rules.
McCain, who lost the 2008 presidential election to Obama, warned that the defeat of any one of the key provisions of the complex legislation could jeopardize the whole effort.
He told reporters that it was "carefully crafted" to keep Republicans, Democrats and different interest groups on board and that if "certain things" were changed, "we would lose one side or the other."
For this and other reasons, Republican Senator Marco Rubio of Florida, another of the bill's sponsors, said the group planned on taking its time with the legislation.
"It's a complicated issue and I think people want to learn more about it," the Cuban-American lawmaker told reporters. "This will be a while. This is not going to be done in a week or quite frankly in a month."
'SERIOUS BORDER SECURITY'
Rubio's comment underscored the delicate construction of the proposal, which would create a new legal status for millions of undocumented immigrants, as urged by immigrant advocacy groups and large segments of the Democratic party.
But to lure Republican support, it conditions a path to permanent legal status - and ultimately a chance for citizenship - on the success of a multibillion-dollar effort to make U.S. borders less porous, using unmanned aerial surveillance, the construction of double and triple lawyers of fencing and the deployment of thousands of additional border patrol officers along with the National Guard.
To get business support, the bill would create a new system of visas for temporary agricultural workers and low-skilled laborers as well as expand the number of specialized, highly-trained foreigners allowed to enter the country to work for technology companies.
To avoid alienating fiscal conservatives in both parties, the proposal denies most federal benefits to the immigrants until they achieve permanent status in the United States, which could take 10 years.
Supporters insist that the bill would not provide an amnesty to illegal immigrants.
The eight senators are trying to pull together broad Republican and Democratic support in hopes that doing so will save the legislation from the fate of failed efforts to comprehensively reform immigration over the past three decades.
That strategy began to pay off Tuesday, even before the bill had been formally introduced.
Conservative anti-tax activist Grover Norquist, head of Americans for Tax Reform, was among those who praised the immigration reform effort. He said he would attend a news conference later this week sponsored by the bipartisan group of senators backing the bill.
"They are doing serious border security. They are making sure that the 10 or 11 million who are here without papers can stay and work as long they are not criminals as long as they're working. So you're weeding out bad guys and allowing people who are good and decent and hard-working to be able to stay and work and get in line in questions of citizenship ..."
Rather than being a cost to the country, the bill would be a "boon" to the economy and would save taxpayers money because those with the provisional visas won't be eligible for federal benefits, Norquist said.
The Senate proposal has been embraced by a range of groups, including the U.S. Chamber of Commerce, the AFL-CIO labor organization and immigrants rights activists.
"As a bipartisan product in a time of hyperpartisanship, it's good, strong policy and I think it's also good enough to attract the kind of bipartisan support it needs to pass," said Frank Sharry, executive director of America's Voice, a group that favors immigration reform.
The bill faces a smoother path in the Senate, where it will move first. A bipartisan group in the House has been trying to craft an immigration bill as well, but has yet to produce one.
Representative Raul Labrador, a Republican from Idaho who is backed by the conservative Tea Party movement, cautioned Congress against moving too quickly to change immigration laws.
"You're going to see legislation going through the (House) judiciary committee. It is going to be slow and methodical," Labrador told reporters.
The argument that the new law would be too costly has struck a chord with Tea Party conservatives and could become a central theme of opposition in the House.
"America's entitlement system is already on a sinking ship and it would be fiscally irresponsible to add another 10 million people to the public assistance rolls," said Debbie Dooley, co-founder of the Atlanta Tea Party.
(Additional reporting by Rachelle Younglai, Kim Dixon, Alina Selyukh, Anna Yukhananov and David Lawder in Washington and Nick Carey in Chicago; Editing by Fred Barbash and Paul Simao)