Every presidential candidate is going to come into the 2012 race with baggage. But Newt Gingrich has what, for primary voters, could be a doozy in his closet -- three years ago, he cut an ad with Nancy Pelosi for Al Gore's climate change group.

The ad, in which Gingrich and Pelosi don awkward smiles while talking about clean-energy solutions, is coming back to haunt him, along with other statements he's made about climate change, as he officially launches his presidential bid. While Democrats have a long and winding list of grievances against the former House speaker, his past environmentalism could cause problems on the political right.

The early complaints are coming in large part from a former aide to Congress' No.1 climate change skeptic, Sen. James Inhofe, R-Okla. The ex-aide, Marc Morano, has virtually devoted his blog ClimateDepot to lambasting Gingrich's stance on energy issues.

Morano specifically wants Gingrich to apologize for the Pelosi ad and for suggesting that lawmakers need to find a solution to global warming.

"It's almost like he can't admit he made a mistake," Morano told FoxNews.com. "He needs to say it was a brain fart, at the very least."

Morano noted that other GOP candidates and officials have modified their stance on climate change and energy regulation in recent years -- particularly former Minnesota Gov. Tim Pawlenty, who at the first presidential debate last week recanted an old environmental ad he cut.

"Newt Gingrich is arrogant enough to believe that he doesn't have to play by the same rules as everyone else," Morano said, predicting it would hurt him in the primaries. "I can't think of any Republican who hasn't addressed this in a way that is satisfactory to the Republican base."

Gingrich's campaign, though, defended the candidate's energy positions, saying he's been the "number one critic" of President Obama's energy policies.

"Newt does not apologize for trying to persuade his ideological opponents that his conservative solutions are the best solutions," spokesman Rick Tyler said in an email. "His attempt to work with Speaker Pelosi is another testament to Gingrich's willingness to debate his conservative solutions with liberals, in this case Pelosi. As it turned out, Pelosi ... and Gingrich still disagree about how to best protect the environment. But Gingrich will never shy away from debating those on the left on issues like the environment, education and healthcare that they think they own."

The 2008 ad was cut for Gore's Alliance for Climate Protection. It showed Pelosi and Gingrich sitting very close on a couch outside the U.S. Capitol.

"We don't always see eye to eye, do we Newt?" Pelosi says in the ad.

"No, but we do agree our country must take action to address climate change," Gingrich responds.

The ad didn't occur in a vacuum. Gingrich for the past several years has trumpeted what he describes as "green conservatism." He co-authored the book "A Contract With the Earth" in 2007, and at the time he talked about the importance of a balanced approach to environmental issues.

In a 2007 PBS interview, Gingrich accused liberals of taking an "anti-market" approach to reducing climate change, leaning too heavily on taxes and other proposals that hurt business.

However, he said the U.S. should still "accelerate the incentive" to reduce carbon emissions and seemed to express support for what's known as a "cap-and-trade" program -- something congressional Republicans and some Democrats have since rejected. Gingrich said at the time that "mandatory carbon caps combined with a trading system" would be "very, very good," in response to a question about an old campaign pledge from then-President George W. Bush.

Tyler, though, said Thursday that Gingrich has "never favored cap and trade because it is essentially a tax of productivity and economic growth."

Gingrich has since raised questions about whether global warming is real. In an interview last year with Human Events, he said: "I don't think we're faced with a crisis of global warming. I think in fact that the scientific data is still very unclear."

The energy plan on Gingrich's campaign website includes a call for "cleaner energy research," but also more domestic drilling and the replacement of the Environmental Protection Agency, which he describes as a job killer.

In an interview with Fox News on Wednesday, Gingrich again stressed the importance of the drilling plank in his energy platform.

"I would reverse Obama's entire pattern of being anti-American energy. I would start by saying drill here. Drill now. Pay less," Gingrich said.