Hartford - Several members of Connecticut's congressional delegation on Friday urged national retailers to take steps to bar guns from their establishments, saying such voluntary efforts could improve public safety and help persuade Congress to pass the gun safety legislation first proposed after the deadly Newtown school shooting.

U.S. Rep. Elizabeth Esty and Sens. Richard Blumenthal and Chris Murphy, all Democrats, sent a letter to the National Retail Federation, urging the 12,000-member organization to take immediate action while also endorsing the 2013 legislation, which included expanded background check requirements for gun purchasers.

While the federal lawmakers said they haven't given up on passing a bill this year, they acknowledged they need to keep building a coalition of people and companies that will put pressure on Congress to do more. Murphy said their mission between now and the end of the year is to move five, six or seven votes so the bill can pass the Senate in 2015.

"These companies have power in Washington, especially with Republican members," Murphy said. "And the changes that they make will not just be cosmetic; they actually can reduce the number of gun deaths across the country."

Some national chains, including Starbucks, have recently enacted policies asking customers not to bring guns inside their establishments. Various national retail establishments have been the scene of shootings in recent years.

Blumenthal said the retailers have "a moral and economic imperative" to speak out on gun violence and to adopt voluntary policies to deter individuals from coming into their stores with firearms.

"We hope that the big movers in the retail industry, like Wal-Mart and Target will follow the lead of some of these other companies because they ultimately can be part of a coalition that will help us get legislation passed," Murphy said.

In a statement, David French, senior vice president of government relations for the National Retail Federation, said the industry is "committed to ensuring that local, state and federal laws are strictly followed and enforced related to the sale of firearms."

French said retailers understand their responsibility and spend considerable time and resources working with law enforcement, elected officials and others "to review and voluntarily strengthen standards so that firearms do not fall into the wrong hands." Also, he said, active shooter training scenarios and staff training are "key priorities for merchants."

"Retailers are keenly aware of the need to provide a safe and secure environment - to whatever extent possible - in their stores for employees and customers alike and work every day to achieve that mission," he said.

Carlee Soto, whose sister Victoria Soto, a teacher, was killed during the December 2012 shooting at Sandy Hook Elementary School, appeared with the Connecticut congressional delegation at a news conference Friday at the Legislative Office Building. She said her heart breaks each time she hears of another mass shooting.

"I can't even begin to understand why nothing has been done," she said. "Millions of Americans have been killed, and no one is taking action. Our leaders in Washington aren't doing enough."