Taking Obama's California Surge With a Grain of Salt

The trend line looks promising for Barack Obama in California. Two days ago, a Zogby poll gave him a one-point lead in the delegate-rich state. Yesterday, his margin swelled to six points. And this morning, the final round of data has him ahead by a staggering 13 points.

But there are two catches:

1) We saw this same kind of trend in the days before New Hampshire, and—amid predictions of a blowout Obama victory—it reversed itself on primary day.

2) California is has some of the most liberal laws in the country for absentee and mail-in voting. Ballots were mailed out a month ago, and it's estimated that more than half of all votes in the primary will have been cast well before today's primary. The problem for Obama is that mail-in voting began back when Hillary Clinton enjoyed a sizable lead in California polls—around 20 points. If that spread was reflected in the early balloting, even a 13-point win among primary days voters won't be enough for Obama to carry the state.