A leading tea party candidate who hopes to knock off venerable Sen. Richard Lugar in next May's GOP primary has campaigned heavily against measures to combat climate change even as he holds stock in an energy company that's banking on those regulations to help build a market for its product.

Indiana Treasurer Richard Mourdock holds up to $350,000 in stock in USA Synthetic Fuel Corp. and its parent company, Global Energy Inc., according to his latest federal financial disclosure filings. The Cincinnati-based companies are seeking financing for a coal-gasification plant in Lima, Ohio, that has been pitched to investors and Obama administration officials as a clean energy alternative to more traditional power sources.

In a filing with the Securities and Exchange Commission, USA Synthetic Fuel said part of its business strategy relies on being able to produce synthetic natural gas cheaper than traditional natural gas suppliers as demand for the fuel grows under expected climate change regulations.

Tea party members and Republicans nationwide say the regulations being pushed by the Obama administration amount to a national "energy tax" because they would increase the overall price of power by limiting cheaper, but dirtier, fuel sources.

Mourdock said his holdings, which he received as payment for geological consulting he did about a decade ago, don't create a conflict of interest because he wouldn't benefit financially if he succeeded in helping block the climate change regulations. He said he hasn't sold the stock because he wants to recoup the money he's owed for his work, but he wouldn't say how much he was owed or whether the stock was now worth that amount.

He said he can't sell his holdings in Global Energy, which could be worth as much as $250,000, because it's not publicly traded.

"I'm trying to get paid for my work," he said.

Mourdock's situation is not a traditional conflict of interest in the sense of him benefiting from policies he's pushing, but it does raise questions of where his allegiances stand: with the tea party philosophy or with his stock portfolio, said Julia Vaughn, spokeswoman for Common Cause Indiana, a public interest group.

"It begs bigger questions in terms of how does he make decisions about what his policies are going to be," she said.

Climate change legislation and the federal health care overhaul helped fuel the rise of the tea party nationwide in 2009. Tea party supporters unhappy with what they called the intrusion of government used both as a rallying cry that led to Republican dominance in the 2010 midterm elections.

While measures to address climate change have almost no chance of ever passing a Republican-controlled House, the Obama administration has charged ahead with its own efforts via the Environmental Protection Agency.

Mourdock, a geologist from coal-rich southwest Indiana, campaigned heartily against climate change legislation in 2009, delivering a speech to the tea-party affiliated Americans for Prosperity and writing a letter to the editor published in newspapers across the state. Then controlled by Democrats, the House passed the bill, but it went nowhere in the Senate.

"The proposed legislation would require businesses to lower their emissions of the so-called 'greenhouse gases' and cause utility prices to increase," Mourdock wrote in the September 2009 letter.

Mourdock told The Associated Press he does not think climate change is manmade or as disastrous as scientists say it is. He also said he will continue to campaign against the environmental regulations being pushed by the Obama administration.

He said he has no plans now to divest the stocks, the values of which are listed only as a range on his federal financial form. The stock in both companies accounts for 5 percent to 28 percent of Mourdock's personal investments.

In forms filed with the SEC, USA Synthetic Fuels said it would be in a good position to take advantage of the Obama-driven climate change regulations because it captures all of the carbon dioxide when it converts coal to synthetic natural gas.

Vice President Dwight Lockwood said his company has always planned to capture its carbon dioxide emissions and believes climate change regulations are inevitable, making it better to be ahead of the curve.

"Our decision to do it is philosophical," Lockwood said. "You can read the tea leaves and know that somebody is going to have to do something, so we may as well get started."

Greg Fettig, co-chairman of Hoosiers for a Conservative Senate, said he opposes the climate change regulations but thinks Mourdock's investment makes smart financial sense.

"He knows coal, it doesn't mean he subscribes to global warming," Fettig said. "I would invest in what I know."