WASHINGTON — After weeks of arguing constitutional fine points and citing rival statistics, senators wrangling over gun control saw and heard the anguish of a bereft father.
Neil Heslin, whose 6-year-old son, Jesse, was among those cut down at a Connecticut elementary school in December, asked the Senate Judiciary Committee on Wednesday to ban assault weapons like the one that killed his child.
‘‘I’m not here for the sympathy or the pat on the back,’’ Heslin, a 50-year-old construction worker, told the senators, weeping openly during much of his hushed 11-minute testimony. ‘‘I’m here to speak up for my son.’’
At his side were photos: of his son as a baby, and of them both taken on Father’s Day, six months before Jesse was among 20 first-graders and six administrators killed at Sandy Hook Elementary School in Newtown, Conn. That massacre has thrust gun control into a primary political issue this year, though the outcome remains uncertain.
The hearing’s focus was legislation by Senator Dianne Feinstein, a California Democrat, to ban assault weapons and ammunition magazines carrying more than 10 rounds. A Bushmaster assault weapon was used at Newtown by the attacker, Adam Lanza, whose body was found with 30-round magazines nearby.
Feinstein said such a firearm ‘‘tears peoples’ bodies apart. I don’t know why as a matter of public policy we can’t say they don’t belong.’’’
Republicans had several answers. They argued that her proposal would violate the Second Amendment’s right to bear arms and take firearms from law-abiding citizens, and said current laws aimed at keeping guns from criminals are not fully enforced.
‘I’m here to speak up for my son.’
‘‘The best way to prevent crazy people’’ from getting firearms is to better enforce the existing federal background check system, said Senator Lindsey Graham, a South Carolina Republican.
That system is designed to prevent criminals, people with mental problems, and others from obtaining guns. It only applies to weapons sold by federally licensed dealers, and expanding that system to nearly all gun transactions is the central proposal in President Obama’s package of gun restrictions, along with bans on assault weapons and large-capacity magazines.
As if to underscore the hurdles Obama’s plan faces on Capitol Hill, House Judiciary Committee chairman Bob Goodlatte, a Republican from Virginia, said he opposed universal background checks such as the president wants, and predicted it would not be part of his chamber’s gun legislation. He wants the current federal background check system strengthened, improving how states provide it with mental health information about citizens and cracking down on illegal gun trafficking.
At the same time, election results from Tuesday highlighted gun control’s potency as a political issue. Illinois state Representative Robin Kelly won a House Democratic primary after a political committee favoring firearms curbs financed by New York City Mayor Michael Bloomberg, Independence USA, spent $2 million on ads for her. Kelly’s foe had opposed an assault weapons ban.
At the Senate hearing, spectators dabbed tears from their cheeks as Heslin described his last morning with his son, including getting a final hug as he dropped him off at school. The hearing room was packed with relatives and neighbors of victims of Newtown, as well as people affected by shootings at Aurora, Colo., and Virginia Tech.