A grassroots group involving several people who lost loved ones in the Newtown school shooting is launching a new campaign to address gun violence, reaching out to parents around the country after seeing its push for new federal legislation fall short in Washington.

The group, Sandy Hook Promise, formed shortly after the 14 December massacre of 26 people at the Sandy Hook Elementary School with the goal of turning the tragedy into a moment of transformation for a horrified nation.

The group announced Thursday that it aims to recruit 500,000 parents to its cause in the month between now and the anniversary of the shootings. Celebrities will be involved, including Sofia Vergara, Ed O'Neill and Alyssa Milano, organizers said.

"I think the lesson that we've learned and the lesson that we've heard from all of these other parents that we've talked to around the country is we don't want to wait for DC," said Nicole Hockley, whose son Dylan was among 20 first-grade children killed in Newtown along with six educators. "Parents don't want to be just told what to do by DC, we don't want to have laws forced on us. Let's tackle the problem ourselves within our communities and in our own schools and let that spread out to affect the nation and affect legislation that way instead of being told what to do."

Other major changes in the country related to drunken driving, smoking and gay marriage stemmed from local conversations that led to legislation later, Hockley said.

Some states, including Connecticut, have passed tougher gun laws since the Newtown massacre. But federal legislation that would have expanded background check requirements for gun buyers fell short by five votes in the senate in April, despite lobbying by some Sandy Hook parents.

Organizers say they're not giving up on national gun legislation, but they acknowledge the uphill nature of the fight and their frustration and disappointment by the lack of action. Mark Barden, whose seven-year-old son Daniel was killed during the shooting, said he hopes the campaign will lead to a cultural change around gun violence.

"We just thought it was time to reset the conversation and look at this from another viewpoint," Barden said.

While the country is polarized over gun control, parents share a common passion for ensuring their children's safety, Hockley said.

"We want to make progress on this by re-establishing that trust by having everyone whether they're a gun owner or a non-gun owner join together as parents to find solutions to the issues that contribute to gun violence," she said. "We have to reset this conversation on a new platform of the love of our children and putting their needs first in order to move forward."

The campaign will raise awareness about programs that could be implemented locally to prevent violence, such as those aimed at reducing social isolation of children, encouraging the reporting of threats and early identification of mental health issues.

For Sandy Hook Promise, the campaign fits in with its original plan to open a dialogue at the local level to pave the way for change.

"This, as we've always said, is a marathon, not a sprint," Hockley said. "Get other people involved because you need a lot of people in a lot of communities to make change happen."