Jay Cost looks at the numbers and sees an incredibly tight Democratic race:
[I]f Clinton can replicate the voting coalition she enjoyed in New Hampshire ... she will all-but-clinch the nomination on Super Tuesday. I would expect her not just to win most states, but to win them by a wider margin. One of the big reasons is that, while Independents were a feather in Obama's cap in New Hampshire and Iowa - they are barred from voting in Alaska, Arizona, Colorado, Connecticut, Delaware, Kansas, New York, and Oklahoma. The key word in the last paragraph is 'if.' We cannot simply assume that Clinton will replicate this coalition. After all, she failed to do it in Iowa. This is actually one of the most interesting dynamics of this primary contest so far.
That's why South Carolina will be such an interesting test. The electorate there is heavily African-American - a constituency which the pundit class seems to think will go heavily for Obama. But the South Carolina Democratic electorate is also downscale - which suggests that it may trend toward Clinton. Unless it doesn't. Here's Cost:
The bottom line: Iowa and New Hampshire diverged in the fullest sense of the word. Not only did Iowa vote Obama and New Hampshire vote Clinton - identical demographic groups broke in opposite directions! This implies that the nomination contest is very much up in the air. The big question is who can put together more of the traditional Democratic voting coalition. Obama did in Iowa. Clinton did in New Hampshire.
In other words: Nothing that has happened so far in this campaign (in either party, one might add) has been dispositive. I wouldn't believe anyone who tells you they know whom the Democratic and Republican 2008 presidential nominees will be.