Sharing a stage with Vice President Joe Biden at a New York City press conference, the father of a boy murdered in Newtown said he was “ashamed” of Congress for not pursuing a federal assault weapons ban.

Neil Heslin, who lost his son, Jesse Lewis, during the Sandy Hook Elementary School shooting in December, was one of several Newtown parents to appear with Biden and New York Mayor Michael Bloomberg at a Thursday press conference.

Heslin was reacting to news this week that there was not sufficient support in the U.S. Senate to include an assault weapons ban in federal gun control legislation.

“No child deserves to be murdered, brutally slaughtered the way these children were, and quite honestly, I’m really ashamed to see that Congress doesn’t have the guts to stand up and make a change to put a ban on these types of weapons,” he said.

In addition to an assault weapons ban, Heslin said Congress should pass laws requiring universal background checks for gun purchases as well as address problems with the country’s mental health system. He said his son was murdered by a “cowardly deranged person with an assault weapon.”

Lynn McDonnell, who lost her daughter Grace, said lawmakers should ask themselves if they were doing enough to “bring about real and meaningful change. And if they are not, to ask themselves ‘Why not?’”

Biden referred to the AR-15-style rifle used in the shooting as a “weapon of war.” He called for a ban on the gun as well as a prohibition on high-capacity ammunition magazines. He said neither ban would infringe on the 2nd Amendment.

Biden said he asks opponents of the bans to think about Newtown.

“Think about how many of these children or teachers may be alive today had [the shooter] had to reload three times as many times as he did,” he said. “. . . Tell me how it violates anyone’s constitutional right to be limited to a clip that holds 10 rounds instead of 30.”

Biden said that the political risk for supporting what he called simple, “common sense” gun proposals has been overstated. He said most of the public, including gun owners, support the proposals.

Bloomberg called on people watching the press conference to call their representatives in Congress and tell them that gun control would be the deciding issue in future elections. For lawmakers who do not support the gun control proposals, he said constituents should support whoever runs against them in the next election, regardless of their political party.

“That is the only way you are going to make a difference here,” Bloomberg said. “Congress just has to get some courage and it’s up to us as Americans and as fellow human beings to sort of give them that courage.”

U.S. Sens. Richard Blumenthal and Chris Murphy both issued press releases on Tuesday expressing optimism that Congress was still moving forward with some legislation in response to the Newtown shooting. Blumenthal said the assault weapons ban was always an uphill battle.

“As we have known all along, we face a marathon and not a sprint,” Blumenthal said.

Gov. Dannel P. Malloy released a statement saying he was “disappointed” by the proposal’s exclusion from federal legislation, but said it did not deter efforts to enact gun violence prevention efforts in Connecticut.