Let's be clear. Mitt Romney hasn't found an answer to a question that he really liked for very long. Ron Paul has some amazing ideas mixed in with some exceptionally odd ones. Rick Santorum alienates too many outside of the far right. Rick Perry was done in Iowa.
The only candidate that Barack Obama has to fear is Newt Gingrich.
Polls be damned. Those who believe that Mitt Romney has a chance against Barack Obama simply need to wait until he's brought before the full focus of the Obama campaign to realize the mistake of that belief. For whatever reason, he is still ambiguous and continues to "consider" releasing his tax returns in April after the nomination is likely to be locked in. Whatever he is hiding, it can be attacked and he knows it.
Ron Paul has been rightfully called the man with the largest floor and the lowest ceiling. His supporters are the most die-hard but he's finding challenges gaining new supporters. If anything, he is identifying himself as simultaneously the most conservative and most liberal depending on the issue and it's simply not a formula that can defeat an incumbent, particularly one who is as strong at debating as Barack Obama.
Rick Santorum was able to sneak into the Iowa race as the non-Romney/non-Paul at the right time. Since entering the spotlight, he has positioned himself as a true conservative who may be able to pull votes from the middle from the anti-Obama moderates. His biggest challenges are his inability to resonate during debates and to pull any of the larger states other than Pennsylvania and Texas.
Newt Gingrich has baggage. He has past issues with ethics, personal morals, and the lack of a filter that polarizes people on certain subjects. Despite these negatives, he's the only candidate that truly worries the Obama campaign because of what could happen if he wins the nomination.
After receiving the loudest applause and the only standing ovation in recent memory during a GOP debate, his performance in South Carolina showed that he's eloquent, passionate, and has ideas that touch on what people want to hear. His concept regarding 99-weeks of unemployment being used for education is a universally-acceptable idea.
In one particular exchange sparked by a question to Santorum about Social Security, Santorum was able to make some strong and realistic points against Gingrich's overly-aggressive plan, but Gingrich's responses received applause while Santorum's rebuttal was met with silence.
Liberals will hate Gingrich more than any of the others. Moderates will fear Gingrich which is one of the main reasons that Romney is leading. These two facts combined may be enough to make Romney the candidate.
This plays directly into Obama's hands.
At this point (and it's way too early to know for sure), Barack Obama is extremely likely to win re-election. Gingrich's abilities, track record, and debating skills are enough to make the Obama campaign worry. Thankfully for Democrats, it's unlikely that the GOP in South Carolina and Florida will be able to see a winner other than Romney while Santorum continues to keep Gingrich behind by splitting the conservative vote with him.
Votes during the next two primaries for anyone other than Gingrich is indirectly a vote for Obama.