WASHINGTON - Even a chocolate bar, it turns out, comes with politics attached.

That peanut butter cup tempting you in the checkout aisle or Krimpet calling out from the office vending machine might seem like sweet, simple bliss, but in Washington they are the subject of fierce debate, competing economic studies, lobbying, and media campaigns that could all spill onto the Senate floor this week.

To hear the combatants tell it, the fight is either over "Big Candy" trying to boost its profits at the expense of good American farmers, or "Big Sugar" squeezing taxpayers to keep its prices high, forcing food-makers and everyday shoppers to pay inflated costs.

The clash has high stakes for Pennsylvania and New Jersey, home to chocolate royalty such as Hershey and Mars. Pennsylvania is the nation's biggest chocolate-producing state, and both states have some of the country's leading concentrations of candy production.

Arguing for its side, the National Confectioners Association website urges visitors to "Vote for Candy." The Coalition for Sugar Reform tells you to "Unwrap the Facts."

Sugar producers, meanwhile, have run a newspaper ad decrying "Big Candy's Greed." It features a photo of $100 bills stuffed into a suitcoat, juxtaposed with a farm that has a sign out front: Foreclosure. Bank Owned.

The bitter debate centers on a federal program that boosts U.S. sugar prices, keeping them well above the world rate with a mix of loans and limits on imports. Sugar-makers say it lets American farmers stay in business in the face of highly subsidized competition from Brazil and Mexico.

But an unusual alliance of lawmakers from candy-producing states has long tried to roll back the program and will take another shot as early as this week, when they hope to push an amendment to a sweeping agriculture bill coming to the Senate floor.

"Virtually every person in America is forced to pay a higher price than they should have to" because of the program, Sen. Pat Toomey (R., Pa.) said in an interview.

It's not just about snacks, he argued, since sugar is also used as a bulking agent and preservative in many foods.

Toomey and Sen. Frank Lautenberg (D., N.J.) are two of 17 cosponsors on a bill from Sen. Jeanne Shaheen (D., N.H.) - whose state is home to Lindt chocolates' American operations - to scale back federal sugar support to 2008 levels, before the addition of some new sweeteners.

The mix of lawmakers backing the bill shows that the fight has a way of melting away political and cultural divides.

At a Valentine's Day news conference, Toomey stood at a lectern holding a box of Corn Flakes. The fiscally conservative Republican railed against the sugar programs' effect on businesses that rely on sugar, grocery prices and jobs, pointing to a nonpartisan study saying the support costs three jobs for every one it saves.

Nearby stood Rep. Earl Blumenauer, an Oregon Democrat wearing a salmon-color bow tie and lapel pin in the shape of a green bicycle.

Blumenauer argued that price supports for sugar encouraged overfarming in the Everglades and resulted in higher costs for an "artesian, Portlandia-type" chocolatier in his district.

The joint news conference was backed by the Coalition for Sugar Reform - which includes both Grover Norquist's free-market group, Americans for Tax Reform, and the environmentally focused Everglades Trust.

The American Bakers Association - which counts Philadelphia's Tasty Baking as a member - is also part of the coalition, as is the confectioners association, whose board includes executives from Tootsie Roll, Pez, and Hershey.

Fifteen Pennsylvania congressmen from across the state and political spectrum are cosponsors of the so-called sugar-reform plan. So are five New Jersey House members. Sens. Bob Casey (D., Pa.) and Robert Menendez (D., N.J.), who each stock their Capitol Hill offices with home-state candy - Hershey's and Mars - have each voted for the plan in the past. (Mars' chocolate division, which makes M&Ms and other snacks, is based in North Jersey.)

Casey said candymakers make "a compelling case."

Pennsylvania has nearly 42,000 jobs tied to sugar-using businesses, according to the coalition, citing 2007 census data. The count is 19,000 in Jersey.

But the American Sugar Alliance says it is also looking out for jobs nationwide: 142,000 tied to sugar farming, largely in Florida and Louisiana, where sugarcane is grown, and Northern-tier states such as Idaho, Minnesota, and Michigan, which produce white sugar beets.

By pressing to eliminate sugar price supports, Big Candy wants "the U.S. industry to go out of business so that they can have very, very subsidized, cheap foreign sugar," said Phillip Hayes, a spokesman for the sugar group.

America would be left to rely on Mexico and Brazil for a key piece of its food supply, he said. He called Brazil, whose government props up its cane farmers, "the OPEC of sugar."

Even when sugar prices plunge, consumers don't see the benefit, said Jack Roney, a sugar alliance executive. "Foodmakers pocket cheaper sugar costs as a profit," he said. The alliance also says the price supports don't directly cost taxpayers anything - though independent reports predict that will change this year.

Each side aggressively advances its arguments. Sugar interests scooped out $7.9 million for lobbying in 2012, according to the nonpartisan Center for Responsive Politics. Hershey and Mars, just two of the big candy companies, combined for $3.8 million.

For 30 years Daniel Sumner has closely watched these fights - once as an assistant secretary in the U.S. Department of Agriculture, now as a professor at the University of California, Davis.

Each time, he has seen the same, well-tested talking points, and the same results: a win for sugar farmers.

"They're the biggest and meanest of the farm lobbies," said Sumner, a strong critic of the program. "Their whole existence depends on this."

In this scrap over candy, there's no room for acting sweet.

at jtamari@phillynews.com. Follow