Past relationships with notorious women have derailed more than one presidential bid.

So former U.S. House Speaker Newt Gingrich had some explaining to do during a visit to this newspaper Friday.

That's because in 2008 he co-starred in a "" commercial, calling for reduction of carbon emissions with -- brace yourself, "conservative" climate-change deniers -- then-House Speaker Nancy Pelosi.

From that 30-second spot:

Pelosi: "We don't always see eye to eye, do we, Newt?"

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

Pelosi: "We need cleaner forms of energy and we need them fast."

Gingrich: "If enough of us demand action from our leaders, we can spark the innovation we need."

And if enough Republican presidential primary voters demand that their party's nominee join Rush Limbaugh in ridiculing the climate-change issue as a liberal hoax, they could cost Gingrich the White House.

Yet Gingrich told us Friday: "I meant exactly what I said in that commercial."

He added that though "nobody knows" every cause of every climate change -- past, present and future -- for sure, "What I said was, 'As a matter of prudence, conservatism ought to involve caution.' "

And he thinks the U.S. ought to vastly boost its use of nuclear power as a way to vastly lower carbon emissions.

He also pointed out that "Contract with the Earth," a 2007 book he co-wrote with Georgia Tech conservation biologist Terry Maple, pushes "a green conservatism."

Gingrich told us he will soon propose "a new model for an Environmental Solutions Agency to replace the Environmental Protection Agency," which he blasted as "anti-business, anti-economic growth."

He said nearly three-quarters of Americans polled think "entrepreneurs, innovators, scientists and technologists can do a better job of solving the environment than bureaucrats, regulation and litigation."

He lamented the "tragic mistake" of Republicans who neglect environmental concerns. He recommended creating "an innovative, market-oriented, incentive-led, conservative environmentalism that's directly competitive with the Sierra Club and that can do a better job than the Sierra Club."

And he rightly hailed the protection of "beautiful sections of this state" as a worthy cause for conservative South Carolinians.

OK, so he also favors offshore drilling -- though way off shore, with drillers required to post "bonds" and "uncapped" damage liability.

Hey, nobody's perfect.

As for his 2008 dalliance with Pelosi, remember, that rose's bloom quickly faded the next year when Gingrich denounced her for contending that she had not been briefed by the CIA about the waterboarding of terror suspects.

From that withering condemnation: "I think she has lied to the House, and I think that the House has an absolute obligation to open an inquiry, and I hope there will be a resolution to investigate her. ... I think this is the most despicable, dishonest and vicious political effort I've seen in my lifetime. ... She is a trivial politician, viciously using partisanship for the narrowest of purposes, and she dishonors the Congress by her behavior."

Gee, and they seemed to be getting along so well in that commercial.

On Friday, though, Gingrich seemed to be getting well along toward making his presidential run official. He said the next step would be forming the obligatory "exploratory committee" at the end of next month.

And while the former congressman from Georgia now lives in northern Virginia, his neighborly awareness of our state extends beyond its precious natural heritage.

For instance, he knows that since our "first in the South" Republican presidential primary began in 1980, each of its winners has gone on to capture the party's nomination.

So South Carolinians should know that the invasion of the GOP presidential wannabes has only begun.