A United States Senate panel yesterday approved a Democratic bill requiring background checks for virtually all firearm sales, seen as a key element of President Barack Obama’s push to reduce gun violence.

The Senate Judiciary Committee voted 10-8 along strict party lines to approve the bill, which would close a loophole that allows unchecked sales at gun shows and on the Internet.

If passed, the bill would result in the most substantial change to US gun legislation in a generation.

But even its main sponsor, Democrat Chuck Schumer, acknowledged it will be difficult to win passage in the full Senate and that lawmakers from both sides could clutter it with amendments.

The White House and Congress have zeroed in on potential measures to reduce gun violence in the wake of the December 14 massacre in Newtown, Connecticut, where a gunman used a semi-automatic assault rifle to kill 20 children and six adults in an elementary school.

The Judiciary Committee also approved a gun-trafficking bill last week that toughens penalties for “straw purchasers,” and signed off on a school safety measure yesterday that would boost funding for school security.

But it put off until Thursday a vote on the most controversial of the four measures: Senator Dianne Feinstein’s revamped version of an assault weapons ban that was allowed to lapse in 2004.

The assault weapons ban and universal background checks are opposed by many Republicans, and Democrats have struggled to find any Republicans willing to sign on to the bills.

“Mass shootings would continue to occur despite universal background checks, criminals will continue to steal guns and buy them illegally to circumvent the requirement,” Republican Senator Chuck Grassley said.

“When that happens we will be back again debating whether gun registration’s needed, and when registration fails, the next move will be gun confiscation,” he said.

The background checks bill would need a 60-vote super-majority to overcome Republican obstruction in the 100-seat Senate. Democrats hold 55 seats so they would need at least five Republicans to go along.

It would then face an even tougher road in the Republican-held House, where several representatives have said they are opposed to universal background checks.