Sean Trende examines the swing state polls and Romney's path to Electoral College victory. An important point:
[M]ost state polls are presently sampling registered voters, not likely voters. Last cycle, moving from a registered-voters screen to a likely-voters screen resulted in a six-point difference in the Republicans’ favor. While the difference will probably be more in the three-to-four-point territory this time, that is nevertheless enough to move a number of the current "lean Democrat" states into the "tossup" category.
The Dish 