I've got a couple of theories about why no Republican front runner lasts for long.
Cain, Perry, Bachmann, Trump, Giuliani, Romney, Palin, Gingrich, Huckabee, Christie all led one or more polls this year. Presumably the list would be longer but the election is still one year off.
It's fun to speculate about why the Republicans are so quickly churning through front runners. My two theories have to do with the inherent contradictions of being a Republican.
One, Republicans are contemptuous of government, convinced that there is almost nothing that government can do as well as the private sector – from pre-school education to funding retirement. Given this, they have even more contempt for politicians than the average person. How does this work when it comes to the rise and fall of political candidates? Well, a fresh face – particularly from the business sector – looks promising for the simple fact that this is not a political face. So, poll numbers go up and very quickly, this candidate looks like a politician. Suddenly, Republican voters remember that they don’t like politicians and the poll numbers for this poor candidate drop as quickly as they rose. Republicans dislike voting for politicians which means, they don't much care to vote for people who run for office. That makes it tough.
Two, Republicans hold at least two contradictory goals. Like those of us who love the idea of six-pack abs and dessert after a cheese burger, Republicans haven’t quite reconciled their love of tax cuts with their contempt for deficits. Even now – with tax cuts at their lowest level in the 50+ years that Obama has been alive – Republicans want lower taxes. And they want the deficit reduced to zero. Anyone who does the math on this quickly realizes how untenable this position is. How does this translate into the rise and fall of political candidates? Well, a candidate who promises tax cuts is embraced …. until he is forced to clarify that he’ll eliminate social security or will ignore deficits or will cut defense spending. Given that no candidate can tell voters how he or she will do the impossible, no candidate has a chance of holding favor.
Republicans have got to feel like the guy who has had a mad crush on that one gorgeous girl all of high school and then – when she finally walks up to him to chat – can’t form a coherent thought or say anything intelligible. The economy continues to stagnate and Obama is terribly vulnerable right now. But the Republicans? They have what has to be their least inspiring and least credible candidates since the party was formed. It wouldn't take much for them to change this: just a willingness to subordinate their ideology to math and necessity (in this case, the necessity of having a government, one inevitably run by politicians).