Right now it seems Romney is way behind in the key states but I think if he can get the national popular vote to swing in his favour it will show in the swing states big time. That's a huge ask though. If he's ahead in the popular vote a lot of states are in play and the map will resemble Bush vs. Kerry 2004 and all of a sudden winning places like Wisconsin and Michigan won't seem absurd. However I don't see him leading the popular vote at all, let alone leading it long enough for it to show in the state polls.
This is a good point. The bitter primary season is doing damage to Romney now, but it's reasonable to assume that his favorability will rise once he becomes the nominee.