Rudy is not the front runner, he is one of those other four who have delegates.
The pattern we saw in South Carolina was when supporters of Rudy picked somebody else they picked McCain, Maybe if Romney did not leave South Carolina to Nevada where he won a solid 51% — things may have been different. We wont ever know because now McCain goes into Florida in a stronger position than what he had going into South Carolina; and Florida may be the start of a rise in his support going straight into Super Tuesday.
For Rudy it is up to Florida, if he can make it anywhere he needs to make it first in Florida; it is up to you Florida, Florida.
According to Survey USA 4 candidates have been in a virtue tie in the state, for some voters — Will voters pick one of the underdogs, if so which one.
The apparent dynamics are Rudy / McCain split the same support and Mitt / Huckabee split the same support (although supporters may be less inclined to switch between the two). McCain appears to be on the way to defeating Rudy and getting his supporters.
[update]
Huckabee sinks in the polls, Romney rises (now leading). McCain and Rudy are tied for 2nd.
[/update]
[update 1-28-2008]
McCain and Romney tied in low 30s for first, Huckabee and Rudy tied in low teens for 3rd place.
[update]
Popularity: 22% [?]