But the consumer sentiment index remains weak, and all the rebound has occurred in Americans' evaluation of future economic conditions, not the present.

Political sentiment is notoriously changeable: What if things begin to go wrong for Obama, and his popularity slumps?

It is possible that the Obama effect will be short-lived if there is a change in people's political sentiment

Some hoped his rise to prominence would have a big impact on white Americans, too, challenging those who still harbour racist sentiments.