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It was just a few months ago when Newt Gingrich’s campaign appeared to be in peril. His entire senior staff resigned en masse, and he and wife Callista were blasted for vacationing in Greece while the campaign was just beginning to gain steam.

Fast forward some four months, and Gingrich has jumped to the top of the polls, becoming — as Herman Cain might say — the “flavor of the week,”  trailing closely behind frontrunner Mitt Romney.

Republicans view Gingrich favorably by 57-23 percent, compared with 50-36 percent for Cain and 42-38 percent for Texas Gov. Rick Perry, according to an ABC News/Washington Post poll released today.

A poll by CNN/ORC International released yesterday also showed Gingrich jumping ahead in the polls. Twenty-two percent of registered Republicans said they would vote for Gingrich, compared to 24 percent for Romney and 14 percent for Cain. In October, Gingrich commanded just eight percent of the vote among GOP voters, less than Romney, Cain, Perry and even Rep. Ron Paul.

Gingrich is riding the wave that first elevated Rep. Michele Bachmann, then Perry and Cain. Republicans are vetting alternatives to frontrunner Romney, who many feel doesn’t bring a freshness that the party needs to win in 2012. Gingrich has acknowledged this much, saying that he is part of an audition “for being the conservative alternative” to Romney.

Gingrich also has the advantage of being a Washington insider without being part of the current medley of politicos. Gingrich was speaker of the House in the late 1990's and was elected to the House of Representatives ten times. Though his time as speaker was fraught with controversy, it has played only a minor part in the current race. Voters view him as a candidate who knows policy, understands how Washington works and has a viable economic plan.

“I may have the best of both worlds, because while I served in Congress and was speaker of the House, I did take the last 12 years off to run four small businesses, write books and make speeches. And so they can look at that and say, you know, he understands the private sector,” Gingrich said in a Fox News interview, when asked about his increasing popularity.

His most recent actions have also helped boost his popularity.

“The explanation for his rise in favorability can probably be summarized in two words: the debates,” said Michael Barone, a fellow at the American Enterprise Institute and a senior political analyst for the Washington Examiner.

Instead of attacking his GOP opponents, like his counterparts, Gingrich has targeted President Obama, a move that has worked in his favor.

“He’s always very articulate. He’s very brave and gutsy in the debates,” said Republican strategist Torie Clarke. “The main thing they [Republicans] have to latch on to right now is the debate. People look at those debates and say, whoever wins this nomination has to go up against Barack Obama in the debate.”

But Gingrich will continue to be haunted by the ghosts of the past, as scrutiny into both his political and private life grows with his rising popularity.

Gingrich has been married three times and took up with Callista, his current spouse, which he was still married to Wife No. 2.

The two racked up to half a million dollars’ worth of debt at Tiffany’s. Gingrich’s financial disclosures revealed that his wife held a revolving charge account at Tiffany and Co. in 2005 and 2006, when she worked at the House Agriculture Committee. Their liabilities at the jewelry store ranged from $250,001 to $500,000 over time.

The two were also lambasted over the summer for going on a cruise in the Greek Isles at a time when they should have been focusing on the campaign. That trip, in part, led to the mass resignation of many of the campaign’s senior leadership, who said Gingrich was not focused on the election.

Gingrich, however, has turned that trip into a political move, saying that it was helpful because he spoke to people there about the economic crisis facing Europe and Greece’s position.

“I was talking with people who were in such trouble that they are facing a one-third drop in their standard of living,” Gingrich said in Iowa on Monday. “And I listened to them and talked to them, I really reflected a lot on what we’re going through.”

Over the summer, Gingrich also faced scrutiny for his nonprofit charity, which came dangerously close to breaking a law that is supposed to separate tax-exempt charitable work from the political process and profit-making enterprises like books and DVDs.

Renewing American Leadership, which Gingrich founded, paid $220,000 over two years to one of Gingrich’s for-profit companies, Gingrich Communications, and bought cases of his books and DVDs made by another Gingrich-run company. The reports by ABC News investigative units stoked questions about Gingrich’s seriousness, and whether he was in the race simply to make money and build his brand. Gingrich and his wife have been promoting their book at virtually every stop on the campaign trail.

Instead of addressing the allegations directly, Gingrich blasted the “elite media” for running “hit pieces” against him.

GOP voters are also questioning whether Gingrich has the discipline needed to win a presidential election. The candidate was blasted by his own staff in the summer for not having focus and discipline, and experts say whether that is still true remains to be seen.

“He cares deeply about these things. Nobody questions his passion,” Clarke said. “But people have wondered, does he have the organizational skills to win. The jury is still outstanding on that.”

It remains to be seen whether Gingrich’s campaign can sustain his popularity. He’s already coming under increased public scrutiny with the recent rise in polls.  Bloomberg reported today that the former House speaker was hired by Freddie Mac as a consultant in 2006 to win GOP allies in Congress, not to advise Freddie Mac as a historian about its business model, as Gingrich said in the Nov. 9 debate.

The former House speaker himself has dismissed the polls, saying he takes them with a grain of salt. Gingrich is instead focusing on expanding his roots.

He recently opened an office in South Carolina, saying, “I believe if we win South Carolina, we’ll win the nomination. If we win the nomination, we’ll win the presidency.”