Ben, my sense is based on the fact that elections are won by and large in the preparation, and Sarkozy and the UMP are much better prepared, in terms of having identified target audiences and in getting their message to them. Royal keeps switching back and forth between trying to appeal to centrist voters (last fall and Jan until she fell behind) and the left (most of Feb and until this week) and now back to centrists. Bayrou is improvising daily.

Sarkozy though knows he needs only to hold enough of the center and is systemicatically pickup off bits of the center/left electorate (eg, he has cultivated Jewish leaders, moderate Muslim leaders, he's appealing to workers, etc) while stoking his base on the right. (To wit, the proposal of a "ministry of immigration and national identity".)

I just think he's got a better organized and more unified campaign; I expect he'll be much better prepared for the second round, as well.