Debates have a reach beyond the immediate bump or slide in the polls as they seep into the narrative and offer up ammunition for campaign commercials. With nearly two full weeks until the next presidential debate, the results of this one have a long time to hang around. Romney's solid performance can lead to new donations that, in turn, lead to better poll numbers in the following weeks.
In this way, debates are the opposite of conventions, in which we advise you to ignore the bump in the polls since they inevitably fade. After debates, we advise you to ignore the non-bump in the polls, because it may grow.
Our prediction moved in Romney's favor because, with the wind in his sails, he is slightly more likely to be able to close the 4.5 percentage point gap in the polls over the next few weeks. That remains, so to speak, an uphill sail..