Newt Gingrich went after candidates who "adopt radically different positions" Monday, positioning himself as a "conservative alternative" to fellow contender Mitt Romney in the race for the 2012 GOP presidential nomination.

Speaking to Charleston, South Carolina radio station WSC, Gingrich said his record was stronger, and more consistent, than the record of the former Massachusetts governor.

"There needs to be a solid conservative alternative to Mitt Romney, and I'm the one candidate that can bring together a national security conservative, and economic conservative, and social conservative, to make sure we have a conservative nominee," said the former House Speaker.

He continued, "I wouldn't lie to the American people, I wouldn't switch my position for political reason. It's perfectly reasonable to change positions if you see new things you didn't see. Everybody does that, Ronald Reagan did that. If you go around and adopt radically different positions based on need for any one election, people will ask, 'What will you tell me next time?'"

Speaking for the first time about Sunday's high-profile endorsement from the New Hampshire Union Leader, Gingrich said it put his campaign in a new competitive mode in the Granite State.

"I think we can have a very serious race with Mitt Romney in New Hampshire, and people didn't think that was possible," Gingrich said.

As for the characterization of him as "by no means a perfect candidate" by the newspaper's editorial writer, Gingrich said no politician could achieve perfection.

"I think anybody who is honest about it says no person is ever perfect," Gingrich said. "I don't claim to be the perfect candidate, I just claim to be a lot more conservative than Mitt Romney and a lot more electable than anybody else."

Gingrich's claim to be the most electable candidate counters the results of a recent CNN/ORC International poll, released last week. Forty percent of Republicans named Romney as the candidate with the best chance of beating President Barack Obama. Only 21% said Gingrich had the best chance of victory. The poll was taken Nov. 18-20.

Gingrich's radio interview kicked off a campaign swing through South Carolina, the first southern state to vote in the primary and caucus calendar.