WASHINGTON — A bill targeting “straw purchases” and trafficking of firearms, co-sponsored by Maine and Vermont senators, has cleared its first hurdle in Washington.

In a bipartisan vote Thursday, the Senate Judiciary Committee approved legislation authored by Republican Sen. Susan Collins of Maine and the committee chairman, Democratic Sen. Patrick Leahy of Vermont.

Collins says the committee vote is the first related to gun violence in either the Senate or the House since the Newtown, Conn., killings in December.

The bill closes a big loophole in federal law by penalizing “straw” purchasers, who buy firearms for another person who is prohibited from obtaining one on his own.

The Leahy-Collins bill is endorsed by several law enforcement groups.

The Democratic-led panel voted 11-7 to impose penalties of up to 25 years for people who legally buy firearms but give them to someone else for use in a crime or to people legally barred from acquiring weapons. The panel’s top Republican, Sen. Charles Grassley of Iowa, cast the only GOP vote for the measure.

President Barack Obama urged lawmakers to vote on gun curbs, including the bill approved Thursday, which lawmakers named for Hadiya Pendleton, the Chicago teenager who was fatally shot days after performing at Obama’s inauguration.

Congress should consider those bills “because we need to stop the flow of illegal guns to criminals, and because Hadiya’s family and too many other families really do deserve a vote,” he said at an Interior Department ceremony.

The parties’ differences were underscored when senators debated a proposal by Sen. Dianne Feinstein, D-Calif., to ban assault weapons and high-capacity ammunition magazines. Democrats have noted that such firearms have been used in many recent mass shootings.

“The time has come, America, to step up and ban these weapons,” said Feinstein, a lead sponsor of a 1994 assault weapons ban that expired a decade later. She added, “How could I stand by and see this carnage go on?”

The response from Republicans was that banning such weapons was unconstitutional, would take firearms from law-abiding citizens, and would have little impact because only a small percentage of crimes involve assault weapons or magazines carrying many rounds of ammunition.

“Are we really going to pass another law that will have zero effect, then pat ourselves on the back for doing something wonderful?” said Sen. John Cornyn of Texas, the No. 2 Senate Republican.

The two other bills would require background checks for nearly all gun purchases and provide around $40 million a year for schools to buy security equipment.

Thursday’s debate made it clear that new gun restrictions face a difficult path in Congress. Obama proposed a broad package of gun curbs in January, including a call for background checks for nearly all gun purchases and an assault weapons ban.

Solid opposition from Republicans, and likely resistance from moderate Democrats in GOP-leaning states, seems all but certain to doom the assault weapons ban when gun bills reach the full Senate, probably in April. The fate of the other bills is uncertain.