WASHINGTON – The food and advertising industries have launched a multipronged campaign to squash government efforts to create voluntary nutritional guidelines for foods marketed to children.

Calling themselves the Sensible Food Policy Coalition, the nation’s biggest foodmakers, fast-food chains and media companies, including Viacom and Time Warner, are trying to derail standards proposed by four federal agencies. The U.S. Chamber of Commerce has also lent its lobbying muscle to the effort.

The guidelines are designed to encourage foodmakers to reduce salt, added sugars and fats in foods and drinks targeted to children. If their products did not meet the standards, foodmakers following the guidelines would refrain from advertising them to children.

The standards would be voluntary and not regulations; companies wouldn’t have to meet them; and the government would have no way to enforce them.

Public-health experts say children, many of whom may lack the critical-thinking skills to understand advertising, are bombarded by TV ads, websites, toy giveaways and cartoon characters promoting junk food. The food and beverage industry spends about $2 billion a year marketing directly to children.

The business community has portrayed the government’s guidelines as job-killing government overreach. Foodmakers said the voluntary guidelines are too severe and would keep them from marketing even relatively healthy foods to children.

Concerned about rising child obesity rates, Congress in 2009 directed four agencies — the Federal Trade Commission, the Centers for Disease Control and Prevention, the Food and Drug Administration and the Agriculture Department — to propose nutritional standards that food and beverages should meet in order to be marketed to kids.

The initiative was led by then-Sen. Sam Brownback, R-Kan., and Sen. Tom Harkin, D-Iowa.

“We allow companies into our homes to manipulate children to want food that will make them sick,” said Margo Wootan of the Center for Science in the Public Interest, which is leading a coalition of groups, including the American Heart Association and the American Cancer Society, in support of the guidelines.

The four federal agencies unveiled proposed standards in May and are accepting public comment through Thursday before finalizing them in a report to Congress.

The business community has sent lobbyists to Capitol Hill, held conference calls for media and produced a print ad extolling its successes in lowering sugar, sodium and fat in many foods marketed to children.

The food industry developed its own standards in 2006 for products marketed to children, but critics say that those efforts lack uniformity and that results have been modest. Foodmakers are updating those industry standards and plan to release a new version of them by Thursday.

Advertising executives touted one economic analysis that suggested the government’s guidelines would kill 75,000 jobs annually, and the U.S. Chamber of Commerce highlighted a legal scholar’s assessment that the voluntary standards would impede commercial speech.

Rep. Jo Ann Emerson, R-Mo., plans to insert a provision in the FTC budget to require the agency to weigh the costs before finalizing the guidelines.

“I’m always worried when voluntary guidelines get pushed, because I fear that it will become prescribed,” she said. “All we want is to do a cost-benefit analysis of the economic impact.”

Foodmakers said the voluntary guidelines could even keep them from marketing foods such as yogurt and whole-wheat bread.

Wootan said that the whole-wheat breads marketed to children would meet the proposed guidelines, as would most of the yogurt now aimed at children.

David Vladeck, director of the Bureau of Consumer Protection at the FTC, said he was surprised by the intensity of the reaction from industry and worried about “misinformation.”

“Congress directed the (agencies) to prepare these guidelines because much of the foods marketed directly to kids are not healthful,” he said. “If you look at rising rates of obesity, one in three kids is either overweight or obese. That percentage is growing. I don’t think anyone thinks the status quo is okay. We are trying to be useful in this debate. This is not stealth regulation in any way, shape or form.”

Overall, records show, the coalition’s main members — including General Mills, Kellogg, PepsiCo and Time Warner — have spent nearly $60 million on lobbying since the start of the Obama administration.

The coalition declined to release its budget for the campaign, which is being managed by Anita Dunn of the firm SKDKnickerbocker. Dunn was White House communications director under President Obama in 2009.

Her work on behalf of foodmakers is surprising to some because first lady Michelle Obama has made childhood obesity her signature issue. In a 2010 speech to foodmakers and retailers, the first lady urged them to curb the marketing of unhealthy foods.

The Center for Science in the Public Interest said Dunn and her firm “should be ashamed.”

Dunn dismissed the criticism.

“Combating childhood obesity is not a question of what gets advertised but a matter of more exercise, healthier eating habits and working together,” she said.