Cook: High Floor, Low Ceiling

Charlie Cook is widely reputed to be one of the 2-3 best political analysts in the U.S. Cook calls this presidential election a close one.

Here in National Journal he says something interesting about President Obama's chances of reelection:

Obama has a high floor, meaning that he has a fervent base of support. He also has a low ceiling, meaning that he has large and adamant opposition. 

In other words, there are fewer people who don't already know how they'll vote in November. However, he reports that Obama's base is less excited about voting than is the Republican base.