A divided Senate Judiciary Committee on Tuesday endorsed President Barack Obama's call to require criminal background checks for all gun buyers, yet it remained uncertain if the measure would become law.
On a party-line vote of 10-8, the Democratic-led panel sent the measure to the full Senate, where it faces a possible procedural roadblock that could kill it.
Federally registered firearm dealers are now required to run background checks on buyers. But about 40 percent of sales are made by private dealers who do not have such an obligation.
Obama proposed background checks for all gun buyers after the school massacre in Connecticut last December, which left 20 children and six adults dead.
Republicans in the committee lined up against the bill, arguing that private gun sales between family members and friends should be exempted from background checks.
They also oppose a requirement that private sellers keep a paper record of firearm transactions, voicing fears that could lead to gun registration and eventually even confiscation.
Democratic Senator Charles Schumer of New York, sponsor of the bill, dismissed such fears as unfounded and argued that the measure would reduce crime.
Schumer also said he was hopeful that a compromise on background checks could be substituted for the committee bill before it goes to the Senate, likely next month.
"We will work non-stop in the next couple weeks to continue negotiating a bipartisan compromise, and we are optimistic we can achieve one," Schumer said.
Senator Charles Grassley of Iowa, the committee's top Republican, led the charge against Schumer's bill, saying, "I don't think it is ready."
"We were told that there would be widespread support," Grassley said, yet three of the four senators Schumer had been working with to reach a compromise did not support the measure he offered.
The committee approved a second bill, 14-4, to provide $40 million a year over the next 10 years to bolster school security. Grassley joined three fellow Republicans and all 10 Democrats on the committee in voting for it.
On Thursday the committee is expected to approve, on another party-line vote, a bill backed by Obama to renew a ban on military-style assault weapons that expired in 2004 after being in force for 10 years.
That measure also faces a possible procedural roadblock, which would require 60 votes in the 100-member Senate to clear.
Republicans and even some Democrats from rural states where guns are popular oppose the ban, arguing it would violate the constitutional right to bear arms. The ban's supporters say they recognize gun rights, but argue that the government has a responsibility to protect its citizens from undue risks.
Military-style semi-automatic assault weapons have been the weapon of choice in a number of massacres in recent years, including the one in Newtown.
With 310 million guns, the United States is one of the most heavily armed nations in the world.
According to a survey of 1,504 adults released on Tuesday by the Pew Research Center, 66 percent of those who live in households without guns say tougher laws would reduce deaths in mass shootings. Just 35 percent of gun owners agree.
Twenty-four percent said they own a gun, and 48 percent of gun owners said they are armed primarily for self protection, compared to 32 percent who cited hunting as the chief reason.
This is a reversal from 1999, when 49 percent said they had a gun mostly for hunting, while 26 percent cited protection as the top reason for owning a gun.