Gingrich, a former U.S. House speaker from Georgia who finished a distant fourth Tuesday in Iowa's caucuses, told MSNBC he and former U.S. Sen. Rick Santorum of Pennsylvania, who lost the Iowa caucuses to Romney but just eight votes, will be "defining Romney out of the mainstream out of the mainstream of the Republican Party."
"By the time he gets to South Carolina and Florida, it will be obvious. This is not a conservative Republican. He is not going to win the nomination. And he is not the most electable candidate. He is simply the guy the news media likes to talk about," Gingrich said.
"I am a Reagan conservative. I helped cut taxes in the 1980s. It created lots of jobs. I helped cuts taxes as speaker in the 1990s. It created 11 million jobs in four years. That's a fact.
"Governor Romney raised taxes, created Romneycare, appointed liberal judges, those are facts. I mean it seems to me you can have an honest, fact-based campaign that draws a contrast between a Reagan conservative and a Massachusetts moderate."
Gingrich decried Romney's negative campaign in Iowa, saying, "I'm the victim of one particular person, Mitt Romney, whose staff went out and decided to run a deliberately negative and dishonest campaign."
Regardless, Gingrich said Romney is a better choice than re-electing President Obama if that's what it comes down to.
"I would support Mitt Romney against Barack Obama because Barack Obama is devastatingly destructive for this country in values and approaches," he said.
After the votes came in Tuesday, Gingrich told about 200 supporters in Des Moines, Iowa, he would take a harder line in the Northeastern state against Romney, The Des Moines Register reported. New Hampshire holds its primary Tuesday.
"We are not going to go out and run nasty ads. We are not going to go out and run 30-second gotchas," Gingrich said. "But I do reserve the right to tell the truth and if the truth seems negative, that may be more of a comment on [Romney's] record than it is on politics."
Gingrich polled just over 13 percent in the Iowa caucuses, well behind Romney, Santorum and U.S. Rep. Ron Paul of Texas.
Notable deaths of 2014 [PHOTOS]