Now it’s Florida’s turn.

Mitt Romney is no longer coasting to the nomination, and Florida — a much different contest than Iowa, New Hampshire and South Carolina — should determine whether Romney’s campaign suffered a temporary setback or is in deep trouble.

Romney is favored to win the Jan. 31 primary, with the average of recent polls showing him ahead by more than 18 percentage points. He has much of the state GOP establishment, especially top fundraisers, behind him. He has by far the strongest campaign organization in the state. He and his allies have already more spent than $7 million on TV ads, including more than $4 million attacking Newt Gingrich, and has plenty more money to spend on TV. He should have a big early lead in the nearly 200,000 votes already cast in Florida — most while all the momentum was on Romney’s side.

Losing Florida could be devastating to Romney, given the advantages he has. And it definitely could happen.

As important as money, television advertising and organization are here, momentum tends to trump everything else in widely watched presidential campaigns. Romney easily outspent and out-organized John McCain in Florida in 2008 and still lost. The nearly 200,000 votes already cast in Florida? That's about 10 percent of the eventual Republican primary vote in 2008.

For all the candidates, Florida presents a very different kind of campaign challenge: the first contest where only Republicans can vote; an enormous state with 10 different and diverse media markets; the first place with a significant number of Hispanic Republicans; and the first primary electorate that truly looks like America — southerners, Yankees and transplants from everywhere else in the country, as well as urban, rural and suburban voters.

Even in an election limited solely to Republicans, whoever wins Florida can reasonably argue they’re best equipped to win in November.