The U.S. Chamber of Commerce is worried that not enough Americans are worried about social safety net spending.

The nation’s largest business lobbying group launched a renewed effort Wednesday to reduce projected federal spending on safety-net programs, labeling them a “ticking time bomb” that, left unchanged, “will bankrupt this nation.”

The effort is aimed at convincing Americans — whom polls show still largely oppose benefit reductions and other changes in Social Security, Medicare and Medicaid — that the nation must rein in spending on these programs.

The effort comes at a time when federal budget deficits are falling from their post-recession peaks, thanks to the tax increases and spending cuts passed in the past two years, and when Americans still rank job creation and economic growth as higher goals for Congress than deficit reduction. It also come as the rate of increase in the cost of government-provided health care is slowing . If that trend persists, it would reduce the size of future deficits dramatically compared with current projections.

Chamber officials expressed concern that those developments could make it tougher to convince Congress now to reduce the amount of benefits that the safety-net programs will pay out in the future.

Business groups and Republican leaders in Washington have pushed the issue aggressively in recent years, but Wednesday they cast themselves as underdogs — against labor unions, senior citizens groups and many Democrats — in the fight to persuade voters to support cuts.

“Entitlement reform will not succeed as long as the conversation is dominated by the overbearing voices of denial and distortion,” Bruce Josten, the Chamber’s executive vice president for government affairs, said in a morning speech to the Chamber’s board of directors.

Taking questions from reporters afterward, he conceded that falling deficit projections were hurting the Chamber’s case — which was why, he suggested, it was time to ramp up warnings about looming budget problems.

Washington is acting as if “all the sudden, the pressure’s off,” Josten said. “All the sudden we don’t need to do anything. It looks good. Well, it looks good temporarily.”

Josten laid out a 10-point case for why Congress must make changes to the programs soon, largely based on familiar arguments: the rising projected costs associated with retiring baby boomers and longer life spans, the crowding out of other federal spending priorities such as education and environmental protection and the potential for massive tax hikes and benefit cuts down the road if more gradual changes are not introduced now.

He and Tom Donohue, the Chamber’s president, said they would not be endorsing specific program changes. Donohue said he would not “throw a proposal out there for everyone and their uncle to shoot at” until Americans accept “a set of facts, realities and truths” about the entitlements.

One of the Chamber of Commerce’s biggest adversaries on the issue, the AFL-CIO, shot back Wednesday, saying that it’s the Chamber that needs to accept reality.

“The Chamber says they want to have this debate out in the open,” said Thea Lee, the labor union’s deputy chief of staff. “We say bring it on. We don’t believe that the American people really want to cut benefits for Social Security, Medicaid and Medicare in exchange for lowering the top tax rate for the richest Americans.”