The state of the Electoral College - 22.07.2012

[pbrower2a]

If anything, summer polling is usually slightly more Republican than the final stretch.

Since about 1990 perhaps. Democrats tend to do much of their vote drives on college campuses in the fall semester. Such would have backfired in the 1980s, when young voters were more conservative than older voters... but that is over.  Many people also start getting some suasion from union vote drives.

These days "likely voters" is a more R sample than "registered voters".