WASHINGTON (Reuters) - The U.S. Senate voted on Tuesday to begin debate and amendments on a historic immigration bill, burying a procedural roadblock that opponents regularly use to delay or even kill legislation.
With November's election results indicating broad support for updating the country's immigration laws, even some senators who have expressed opposition to the Senate bill voted to allow the debate to go ahead.
By a vote of 82-15, the Senate cleared the way for the long-anticipated debate that could extend through June.
Opponents of the bill quickly offered amendments to significantly change or possibly kill the measure if adopted.
Republican Senator Charles Grassley of Iowa introduced a plan requiring the Obama administration to certify "effective control over the entire southern border" for a period of six months before any of the 11 million undocumented residents in the United States could begin applying for legal status.
"Border security first, legalize second," Grassley said.
Other Republican senators are pushing similar proposals.
The legalization and ultimate citizenship for the 11 million is a central component of the bill. Democrats and some Republicans have vowed to block any measure that leaves their fate in doubt indefinitely.
Earlier on Tuesday, President Barack Obama sought to inject momentum into the push for U.S. immigration reform.
"If you genuinely believe we need to fix our broken immigration system, there's no good reason to stand in the way of this bill," Obama said at the White House just hours before the Senate staged its first vote on the measure.
"If you're serious about actually fixing the system, then this is the vehicle to do it," he said.
Obama, who won re-election last year thanks in part to strong support from Latino voters, has made immigration reform a top priority of his second term.
He had not given a major public address on the issue for some time, reflecting a White House strategy of not wanting to get in the way of the bipartisan bill's progress in the Senate.
Obama's speech on Tuesday was the first major departure from that strategy.
The Senate bill would authorize billions of dollars in new spending for enhanced border security and create new visa programs for high- and low-skilled workers in addition to providing a pathway to citizenship for the roughly 11 million undocumented immigrants - many from Mexico and Central America - currently in the country.
As Congress plunged into a contentious debate on the bill, freshman Senator Tim Kaine of Virginia, a Democrat, delivered a Senate speech in support of the bill in Spanish.
Senate officials said it was the first time in at least decades that a floor speech was spoken entirely in a language other than English.
The bill, which has broad support from Obama's Democrats, will need backing from some Republicans in order to give it momentum in the more conservative, Republican-controlled House of Representatives, where the pathway to citizenship provisions face deeper skepticism.
Four Republicans joined with four Democrats in writing the Senate bill earlier this year.
In a sign of the hurdles to come, House Speaker John Boehner of Ohio said he expected immigration reform to be law by the end of the year. But he said the Senate measures to enforce the changes and secure the U.S. border with Mexico were inadequate.
And Senate Republican leader Mitch McConnell of Kentucky warned in a speech in the Senate: "In days ahead there will be major changes in this bill if it is to become law."
Immigrant groups fear that too many changes could erode a delicate coalition now pushing the bill.
Boehner, the top Republican in Congress, told ABC television in an interview that aired on Tuesday: "I've got real concerns about the Senate bill, especially in the area of border security and internal enforcement of the system. I'm concerned that it doesn't go far enough."
Boehner added that reforming the nation's immigration system was his top legislative priority this year.
"I think by the end of the year we could have a bill," he told ABC. Asked if that bill would be one to also pass the Democrat-led Senate and be signed into law by Obama, Boehner said: "No question."
Additional reporting by Mark Felsenthal, Roberta Rampton, and Susan Heavey; Editing by Paul Simao and Cynthia Osterman