All aboard the Herman Cain train

Herman Cain – the former CEO of Godfather's pizza – has gone from virtual unknown to frontrunner in a matter of months. In both of the national polls realeased this week, he leads Mitt Romney by four points.

Gallup's favourability ratings are a good way of tracking the popularity of the candidates. The chart below provides a pretty good illustration of the race so far. It shows Perry's quick rise when he entered the race in August, and his even quicker fall following his first debates in September. You can also see Cain's gradual rise after that strong debate performance in May, and his much steeper rise in the past month. And through it all, Mitt Romney's support remains steady, if unspectacular:

Cain now has the highest "favourable" – and lowest "unfavourable" – numbers of the entire Republican field. He's on top of the polls both nationally and in states across the country: from Texas to Hawaii, Ohio to South Carolina and – crucially – Iowa.

And yet his chances of winning the nomination are still considered pretty slim by most. Ladbrokes has him at 8/1 – behind Romney at 4/7 and Perry at 3/1.

Why so sceptical? Perhaps it's because we've already seen other candidates (Trump, Bachmann and Perry) surge to the front before dropping away. Many pundits forecast a similar fate for Cain. Then there's the claim that he's not a "serious candidate": promoting his book in Texas instead of campaiging in Iowa and joking about an electric border fence. And he's not helped himself be putting out decidedly weird ads.

Most importantly, though, Cain's campaign lacks the fundamentals asssociated with a successful candidate at this stage. Nate Silver puts it best at Fivethirtyeight:

"Mr. Cain has no endorsements from Republican members of Congress or Republican governors, and very few from officials in key early voting states. He has raised very little money. He has not hired well-known names for his campaign staff. He does not have traditional credentials. He has run for elected office just once before."

"There is simply no precedent for a candidate like Mr. Cain, one with such strong polling but such weak fundamentals."