* Democratic-led panel expected to back four bills
* But unclear which if any of them will win Senate approval
* Dispute arises over background checks for gun owners
Less than three months after the Connecticut school massacre, members of a Senate committee on Thursday will cast the first votes in Congress on measures backed by President Barack Obama to tighten U.S. gun laws.
The Democratic-controlled Senate Judiciary Committee is expected to approve the four bills that make up the gun-control package in votes over the next day or so.
That will set up battles in the full Senate over a proposed ban on assault weapons and expanding background checks on prospective gun buyers.
Wider background checks had been seen as having a good chance in Congress, but the effort has stumbled in recent days over a dispute about whether to keep records of private gun sales. Republicans fear such records would be a first step to a government register of gun owners.
Republican Senator Tom Coburn of Oklahoma appeared more optimistic on Thursday about the possibility of reaching an agreement with Democrats on background checks.
"I think we'll ultimately get there even though the outside groups aren't comfortable with it yet," Coburn said on MSNBC's "Morning Joe."
The drive for gun-control laws has taken on a new urgency since the December shooting in which a gunman killed 20 children and six adults at a school in Newtown, Connecticut.
It has become one of Obama's top domestic priorities, along with immigration reform and fixing a series of budget messes.
But reviving an assault-weapons ban that expired in 2004 has almost no chance in Congress, with opposition from Republicans and some Democrats.
The two parties are closer to agreement on the two lesser elements of the gun-control drive: cracking down on the illegal trafficking of firearms and bolstering school security.
Prospects for the measure to combat unlawful gun trafficking improved on Monday when Senate Judiciary Committee Chairman Patrick Leahy, a Vermont Democrat, picked up four co-sponsors - two Republicans and two Democrats.
The panel's top Republican, Senator Charles Grassley, said he might also back the measure, which would toughen statutes against "straw purchasers," people who profit from buying guns then selling them to those prohibited from owning firearms.
"The practice of straw purchasing is used for one thing - to put firearms into the hands of those that are prohibited by law from having them. Many are then used to further violent crimes," Leahy said on Tuesday.
Senator Barbara Boxer, a California Democrat, has gained bipartisan support for her measure to provide $40 million a year for 10 years in matching federal grants to schools to strengthen security.
It would authorize the U.S. Justice Department to create a National Center for Campus Public Safety to serve as a clearing house for best practices and information.
"Congress spends hundreds of millions a year to protect its members. It can certainly spend $40 million a year to protect our children," Boxer said on Monday.
Democrats control the Senate Judiciary Committee 10-8 but they might need 60 votes to clear gun control legislation in the 100-member Senate where they have only a 55-45 majority.