Editor's note: Julian Zelizer is a professor of history and public affairs at Princeton University. He is the author of "Jimmy Carter" (Times Books) and author of the forthcoming book "Governing America" (Princeton University Press).
Princeton, New Jersey (CNN) -- With his victories in Florida and Nevada, Mitt Romney has re-emerged at the front of the GOP pack.
Given the primary and caucus schedule for the rest of February, it will be extremely difficult for Newt Gingrich to regain the momentum that he had after South Carolina. Romney finds himself in a strong position to win the nomination.
Although there have been countless stories in the past few months about the latest "Anyone But Romney" candidate who was going to steal the crown from him, the former Massachusetts governor is still standing.
The reasons for Romney's success have been widely discussed. Most of the explanations are less about him than about his opponents. In rather consistent fashion, commentators have argued that Romney remains the most "electable" candidate and, in the end, this year Republicans voters are going to make their decision based on who has the best chance of defeating President Barack Obama.
But there is more to Romney's success than the perception about his electability or his good looks. A variety of other factors have made Romney into a much stronger candidate than in 2008 and produced a campaign that keeps proving to be more formidable than expected.
The first factor is money. One thing that Romney has been very good at is raising campaign contributions. His opponents have been unable to match his prowess on the fundraising circuit. His campaign amassed $24 million in the final quarter of 2011. Gingrich raised nearly $10 million in that same period. The result is that Romney has accumulated a war chest that far outpaces his opponents.
Money matters in campaign politics, and Romney demonstrated how it could be put to good use in Florida. According to ABC News, Romney spent $7 million in Florida and a supportive super PAC spent $8.2 million, compared with $1 million by Gingrich and $2.2 million by the super PAC that has backed the former speaker.
Through a blistering advertising campaign, Romney and his supporters brought up all of Gingrich's baggage and effectively framed him as an unpredictable politician with a record of corruption and hypocrisy.
The second factor is Romney's steadiness. Even with all the ups and downs and twists and turns of the campaign, Romney has remained extremely disciplined. He has not panicked during the various media frenzies that he has confronted.
As numerous commentators have pointed out, this is in part as result of the experience of his father, Michigan Gov. George Romney. Though considered to be one of the strongest Republican contenders for the 1968 Republican nomination, his candidacy crashed and burned when he made a comment about the "brainwashing" he thought he had received from generals and the diplomatic corps during a trip to Vietnam (Romney was trying to explain why he now opposed the war). The comment turned him from the candidate who was likely to win in 1968 to the candidate who would never have a chance.
Mitt Romney has generally remained on message. He has continued to stick to his themes of having experience in the private sector and as governor, and he has continually boasted that his financial and managerial resume makes him a candidate who can win and do well as the nation's leader.
He has stayed away from most of the social issues and remained generally calm during the most heated moments of the debates. He has certainly suffered through many verbal slip-ups, such as his recent statement about not caring about the very poor.
In response to questions about his economic proposals, Romney told Soledad O'Brien, "I'm not concerned about the very poor. We have a safety net there. If it needs repair, I'll fix it. I'm not concerned about the very rich. They're doing just fine. I'm concerned about the very heart of America, the 90 to 95 percent of Americans right now who are struggling."
The comment caused a firestorm, but he has shown the ability to remain calm in the aftermath and stay focused until the media turns its gaze elsewhere. Although Romney has not enjoyed the huge upticks that other candidates like Gingrich and Rick Santorum enjoyed, neither has he really suffered from their downturns -- other than in South Carolina.
The final factor has to do with how Romney handled the most devastating attack he confronted. Gingrich went after Romney's background in Bain Capital by depicting him as a "vulture capitalist" who left unemployed bodies wherever he went in pursuit of profit.
At a critical moment, Romney responded by turning the attack in his favor. He portrayed himself as the defender of market capitalism. In doing so, he turned attacks on his background into attacks on the free market.
"We've understood for a long time that the Obama people would come after free enterprise," he said, "Little surprised to see Newt Gingrich as the first witness for the prosecution..." In conservative circles, this response dampened some of Gingrich's fire.
All of these factors have made Romney into a stronger candidate than he is often portrayed to be. But there is a big difference between winning the nomination and winning the general election. In a contest against President Barack Obama, the attacks on his record with Bain will play much better in Democratic circles as well as among independent voters than they have with the GOP.
If the economy continues to improve, it could easily dampen Republican criticism on the administration's policies and its claims to be the party that has the best grasp of how to stimulate economic growth.
For all his problems, Obama is also building a huge war chest of campaign contributions and will be able to continue his advertising assault on Romney. The president raised $68 million in the final months of 2011. Finally, the steadiness that Romney has displayed will certainly be severely tested in the fall as the national campaign heats up -- and there will be many more opportunities for slip-ups, mistakes and tense moments in front of the cameras.
But for now, Romney has remained the Teflon candidate of the 2012 race as he moves closer to the Republican nomination.
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The opinions expressed in this commentary are solely those of Julian Zelizer.