By Patricia Zengerle and Warren Strobel
WASHINGTON, June 2 (Reuters) - The U.S. Senate voted to move ahead on Tuesday with a bill that would end the ability of spy agencies to collect Americans' telephone records in bulk and install a more targeted system, but a political fight loomed over potential changes to the bill.
The procedural vote of 83-14 limited debate on legislation known as the USA Freedom Act but arguments over how to balance Americans' concerns about privacy and fears of terrorism, which had already held up the bill, could stall it further.
Three domestic surveillance programs authorized under the USA Patriot Act, passed after the Sept. 11, 2001, attacks have been shut down since midnight on Sunday, after the Senate missed a deadline to extend legal authorities for certain data collection by the National Security Agency and Federal Bureau of Investigation.
Senate security hawks have proposed four amendments they say would plug important holes in the surveillance system outlined in the Freedom Act, which passed the House of Representatives by a 338-88 vote on May 13.
Among other things, their amendments would give the National Security Agency 12 months, instead of six months, to wind down its existing collection of bulk telephone "metadata." They also want the Director of National Intelligence to certify that the new system works.
"Before scrapping an effective system that has helped protect us from attack in favor of an untried one, we should at least work toward securing some modest degree of assurance that the new system can, in fact, actually work," Senate Republican Majority Leader Mitch McConnell said.
Privacy advocates, however, who have opposed the program since it was exposed by former NSA contractor Edward Snowden two years ago, have balked. They say the changes would weaken privacy protections in the Freedom Act and hold up the bill.
"All of the amendments would delay passing an excellent piece of legislation, one that's been worked on by Republicans and Democrats for months and months, some would say years," said Democratic Senator Patrick Leahy, an author of the Freedom Act.
The changes proposed in the Freedom Act could alleviate concerns of a federal appeals court, which ruled on May 7 that the programs as outlined in the Patriot Act were illegal.
Another amendment would strip a provision now in the bill allowing outside experts on privacy and civil liberties to argue in some cases before the secret Foreign Intelligence Surveillance Court.
Senate rules provide for up to 30 hours of debate before lawmakers vote on amendments, although Senate leaders said they expect votes later on Tuesday.
If any of the amendments pass, the amended measure would have to be sent back to the House for its approval before it could be sent to the White House for President Barack Obama to sign into law.
Obama strongly supports the Freedom Act, and the White House has said the proposed amendments seem unnecessary.
The amendments, if passed, could also cause problems in the House.
Kevin McCarthy, the House' Republican Majority Leader, warned the Senate to approve the House-passed bill, as is.
"My advice is to take this bill and pass it," McCarthy said at a news conference, adding that Senate changes to the bill could present "challenges" in the House.
Two senators who helped block proposed extensions of the existing surveillance programs offered their own slate of nine amendments to the Freedom Act on Tuesday.
Among other things, Republican Rand Paul and Democrat Ron Wyden want to require the government to get a warrant before collecting personal information from third parties, make it easier to challenge the use of illegally obtain surveillance information in criminal proceedings, and raise the standard for government collection of telephone records. None of those amendments was expected to come up for a vote in the Senate. (Additional reporting by Susan Cornwell; Editing by Grant McCool)