(CNN) - Republican Senate candidate Rob Portman released a new TV commercial Tuesday touting his opposition to cap-and-trade language in new energy legislation, but Ohio Democrats quickly accused the former congressman of flip-flopping on the issue.
In the 30-second ad, Portman calls cap-and-trade "a new energy tax" that's "a job killer for Ohio."
"We're taxed turning on a light, using our computer, or even cooking dinner," Portman says.
But Democrats have latched onto two lines from a column penned by Portman when he was a congressman in 1996.
"Private sector incentives, such as permitting companies to trade discharge outputs, can both reduce pollution and costs," Portman wrote. "If we can harness the power of market incentives, we'll do more with less."
Ohio Democratic Party spokesperson Haley Morris says that's a flip-flop.
"Just like the Big Bank Bailout, Congressman Portman was for Cap and Trade before he was against it," Morris said in a statement. "The only thing Ohioans learn about Congressman Portman from this ad is that his positions go whichever way the wind blows."
But Portman spokesperson Jessica Towhey said what the former congressman proposed is not the same as cap-and-trade, and points to another line from his column that indicates his stance has remained unchanged.
“Sometimes, one-size-fits-all environmental regulations from Washington are imposed at a huge cost to the economy with little or no benefit to the economy," Portman wrote.
"Seems pretty consistent with what he’s saying today," Towhey said. "The one-size-fits-all regulations is the definition of the cap-and-trade energy tax that’s supported by Lt. Gov. Fisher."
"Incentives are very different from the cap-and-trade plan, which calls for mandatory caps," Towhey said.
Climate change legislation has been stalled in the Senate after the House of Representatives passed its own energy bill last year. The House plan included the so-called cap-and-trade system in which a price is set for greenhouse gas emissions such as carbon dioxide and polluters can obtain and trade credits for emissions over a set threshold. Most Republicans are against such a plan.
Portman will face off in the general election against Ohio Lt. Gov. Lee Fisher to fill the seat of retiring Republican Sen. George Voinovich.