Gingrich has pledged to make near-daily appearances in the state ahead of the January 3 caucus, while longtime frontrunner Romney -- now under enormous pressure to prove his staying power -- this week launched his first Iowa ad.
Romney, a former Massachusetts governor, until recently appeared to be the favorite to take on Democratic President Barack Obama in the November 2012 elections despite his failure to energize his party's conservative base.
But strong debate performances by Gingrich, a former speaker of the House who was a giant of Republican politics in the 1990s, shot holes in Romney's default favorite status.
Major gaffes by Texas Governor Rick Perry and the spiraling troubles of Herman Cain -- now facing sexual harassment allegations and claims that he had a 13-year extramarital affair -- have narrowed the field.
In what looks increasingly like a two-horse race, Gingrich got a massive boost when he surged to the largest national lead held by a Republican candidate, according to a poll released Thursday by Rasmussen Reports.
Gingrich won 38 percent support among likely Republican voters, while Romney placed a distant second with 17 percent. No other candidate reached double-digits.
"It is a game changer," said Trey Grayson, director of Harvard University's Institute of Politics.
"Romney has got to be considered the favorite but I think Gingrich's surge is real and appears to have more staying power than other surges we've seen from other candidates."
An Iowa win would give Gingrich's campaign significant momentum, especially if he could follow up a week later with a win in New Hampshire, where he has already received a key newspaper endorsement.
Romney, who has benefited from a much-better funded campaign, has until now been focusing his efforts elsewhere in hopes that he can reap dividends from the work he put into Iowa in his failed 2008 bid.
But he has made multiple Iowa stops in recent weeks.
Timothy Hagle, an associate professor of political science at the University of Iowa, said Romney's efforts will not be in vain, if he continues to boost his scheduled appearances in the coming weeks.
"When he is here, he has been fairly well received, but people want him to answer questions and meet with them. That's the way it works. You can't just issue one advertisement and think that's the end of it," Hagle said.
Romney's campaign has remained relatively tight-lipped on how or it its campaign tactics have changed in the wake of the Gingrich surge, but he has sharpened his attacks on the former Georgia congressman.
"If America feels that we need somebody who's lived in Washington for the last 40 years to run the country, then he's a good choice," Romney said Friday in an interview on Fox News.
As for Gingrich, he told reporters in Iowa Thursday: I'm not interested in distinguishing myself from Romney. I'm happy to be who I am."
Though some polls suggest Romney has a better chance than Gingrich of defeating Obama, there is still a major "anyone but Romney" contingent within the Republican party that remains unconvinced he is their man.
Democrats have focused a full-fledged attack on Romney -- a possible sign that they would rather face Gingrich next year.
Gingrich was recently forced to deny lobbying on Freddie Mac's behalf after reports emerged that he earned at least $1.6 million from the government lender between 1999 and 2008.
The confessed adulterer has also divorced twice and left his first wife following her treatment for cancer -- actions likely to turn off many social conservatives.
Gingrich's campaign in May had a rough start after a number of missteps that left $1 million of debt and barely registered in the polls.
But some voters are now giving him a second chance.
"I've always said I would vote for him if I thought he had a legitimate chance," said Chris Dowd, an Iowa Republican. "There's a very good chance I'll support him in the caucuses now."
Dennis Goldford, a professor of political science at Drake University, contends that Gingrich's rise is largely out of Republican exhaustion over the search for a Romney alternative.
"Romney is the guy your mother wants you to marry," Goldford said. "He's good-looking, he's got money but he just doesn't get your heart racing whereas Gingrich is the walk on the wild side."
The two men next face off in a candidate forum on Saturday. A closely watched poll of Iowa voters by the Des Moines Register will also be released Saturday.
