ARE YOU glugging down a cold Coca-Cola to beat the heat?

Well, that shiny, red can isn't just holding a refreshing beverage. It's the center of an ongoing political battle that still has a whole lot of fizz left in it.

Despite two failed attempts to enact a local tax on sugar-sweetened beverages — in both 2010 and 2011 — Mayor Nutter is not ruling out another attempt to help fight obesity and boost revenues. As interest in this tax grows nationally, Nutter has become a leading voice on the issue, giving a keynote speech last month at the National Soda Summit, a public-health meeting in Washington.

"It was a good idea when we proposed it; it's still a good idea today," Nutter said this week.

Nutter's speeches on soda and obesity have not gone unnoticed by opponents of the tax — which include soda companies, union workers and merchants. Those groups say that there are other ways to fight obesity and that the tax would kill jobs. Although Nutter made clear that he wouldn't seek a soda tax in 2012, lobbying reports for Philly show that the single biggest spender for the first three months of the year was the American Beverage Association, which laid out $238,921 to advocate against a soda tax.

"We have been vigilant since the last time the mayor tried to enact a sugar-sweetened-beverage tax," said Frank Keel, a spokesman for Teamsters Local 830, which represents bottlers and drivers at four regional bottling plants. "We have every reason to believe it's coming back."

A soda tax seemed like a novel idea when Nutter first raised it in 2010. Now similar proposals are under debate in more cities, as municipal governments battle both dropping revenues and expanding waistlines. Voters in Richmond, Calif., will decide on a soda tax in November. And New York City Mayor Michael Bloomberg wants to restrict the size of sodas sold in the city's eateries. "It's certainly more in fashion than when he first introduced it," said Zack Stalberg, president of the Committee of Seventy.

Nutter said that if he had been successful in getting City Council to approve a sweetened-beverage tax — which he twice proposed at 2 cents an ounce — the city would have more revenue now to help the financially troubled school district. He blamed the defeats on the power of the soda lobby, saying that his political skills were not the issue.

"They are a powerful lobby, much like the NRA, much like big tobacco, and they seek to intimidate legislators at all levels of government," Nutter said. "And in the meantime their product does have a negative impact on people's health."

Still, if Nutter wanted to go another round, he'd be up against the same powerful forces that defeated the tax twice before — and a City Council that may not be any more sympathetic. Political consultant Larry Ceisler, who works with the Philly Jobs Not Taxes coalition funded by the beverage association, said that the group wants to fight obesity but thinks the mayor should look elsewhere for revenues.

"We've always felt — and I think we've been proven right — that in Philadelphia for the most part the soda tax is a revenue play," Ceisler said. "Our coalition has hoped to partner with the mayor in the fight against obesity."

The next budget season is months off, but both sides on the soda-tax issue are aware that Nutter likes to play the long game.

"Let's not forget it was six years trying to make Philadelphia smoke-free," Nutter said, referring to the smoking ban he passed while on City Council. "And everyone knew that smoking was bad and everyone knew secondhand smoking was bad."