(ABC News) -- A father who lost his son in the massacre at Sandy Hook Elementary School sobbed as he testified at a Senate hearing today in favor of an assault weapons ban.
Across town Vice President Biden alluded to untold horror of the Newtown tragedy in an appeal for help from the nation's attorneys general.
Despite their emotional appeals, the push for gun reforms championed by the White House and many Democrats faces an uncertain future.
"Jesse was the love of my life," said Neil Heslin, sobbing as he described his 6-year-old son before the Senate Judiciary Committee. "He was the only family I had left. It's hard for me to be here today to talk about my deceased son. I have to. I'm his voice."
Heslin's son, Jesse Lewis, was among the 20 children and six teachers and school administrators murdered at Sandy Hook Elementary in Newtown, Conn. last December. Heslin recounted his last moments with his son when he took him to pick up his favorite, sausage egg and cheese sandwich and hot chocolate before dropping him off at school on the morning of Dec. 14.
"It was 9:04 when I dropped Jesse off. Jesse gave me a hug and a kiss and at that time said goodbye and love you. He stopped and said, I loved mom too." Heslin and his wife are separated.
"That was the last I saw of Jesse as he ducked around the corner. Prior to that when he was getting out of the truck he hugged me and held me and I could still feel that hug and pat on the back and he said everything's going to be ok dad. It's all going to be ok," Heslin said breaking down in tears a second time. "It wasn't ok. I have to go home at night to an empty house without my son."
Heslin was one of eight witnesses testifying at a hearing to back a proposed assault weapons ban. Another witness was Dr. William Begg, a physician who made it to the emergency room the day of the Newtown shooting.
"People say that the overall number of assault weapon deaths is small but you know what? Please don't tell that to the people of Tucson or Aurora or Columbine or Virginia Tech, and don't tell that to the people in Newtown," Begg said as he choked up and people in the crowd clapped. "Don't tell that to the people in Newtown. This is a tipping point. This is a tipping point and this is a public health issue. Please make the right decision."
The Senate Judiciary Committee is set to consider four gun safety measures, including the assault weapons ban, on Thursday. The three other bills aim to stop illegal gun trafficking, enhance safety in schools, and enact universal background checks.
As the hearing unfolded on Capitol Hill, Biden tapped into the stories that Newtown's first responders have shared with him as he urged attorneys general to help the administration push their gun proposals.
"With the press not here, I can tell you what is not public yet about how gruesome it was," Biden said of the massacre's gruesome aftermath at a Washington luncheon. "I met with the state troopers who were on the scene this last week. And the impact on them has been profound. Some of them, understandably, needing some help."
A spokeswoman for Biden could not clarify the non-public information to which he referred. The vice president suggested that what he heard in private conversations should spur lawmakers to enact some measures aimed at curbing gun violence.
Many of the first responders have remained out of the public eye in the weeks since the tragedy, keeping their personal grief and emotional trauma private.
"The excuse that it's too politically risky to act is no longer acceptable. We cannot remain silent," Biden said in an impassioned plea. "We have to become the voices of those 20 beautiful children who 75 days ago were killed. They can't speak for themselves.
"You know better than any elected officials," the vice president said. "We have to speak for the more than 2,000 people who have died at the end of a gun just since Newtown -- 2,000 Americans in 75 days."
The vice president is also meeting with New York Mayor Michael Bloomberg, another gun control advocate, to discuss the administration's gun violence proposals. He acknowledged differences of opinion in how to best address the epidemic of gun violence, but said attorneys general are well-positioned to bridge a partisan divide.
"All of you, unlike any other elected official in your state, are cloaked with both a moral and political credibility that no other office holds," Biden said. "Each of you are able to operate in an area that is not viewed as a partisan bloodbath.
"I need your advice and I need your help, and I mean that sincerely," he added. "No one has ever doubted that I mean what I say, the problem is I tend to say all that I mean, and that gets me in trouble."
One of the most contentious moments of today's hearing highlighted the difficulty of passing any gun control legislation. Sen. Lindsey Graham, R-S.C. asked witnesses about prosecutions for those who foiled current legislation that requires background checks for most gun purchases.
An increase in background checks to include people who buy weapons from gun shows and from individuals is one aspect of the gun control debate that has wide support. Graham said the existing laws should first be better enforced.
"If we're going to require background checks, it looks to me like we ought to start enforcing the law that's on the book," Graham said. "I'm a bit frustrated we say one thing about how important it is, but in the real world we absolutely do nothing to enforce the laws on the books."
Sen. Dianne Feinstein, D-Calif., who introduced the assault weapons ban, recounted the violence inflicted at a number of mass shootings involving assault style firearms as an example for why such kinds of weapons should be banned.
"That horrific event shocked our nation to its roots. And the pictures of these little victims brought tears to the eyes of millions of Americans. We are holding today's hearing because the massacre in Newtown was sadly not an anomaly," Feinstein said. "We cannot allow the carnage I have described to continue without taking action on what is a serious matter of public policy."
Sen. Chuck Grassley, R-Iowa, argued, that limiting the types of firearms people can purchase is not the way to stop criminals from committing acts of violence.
"When something has been tried and found not to work, we should try different approaches rather than reenacting that which hasn't done the job. There are vast numbers of gun-control laws in our country. Criminals do not obey them, but law-abiding citizens do. That tilts the scale in favor of criminals who use guns," he said.