Assuming Romney's the nominee, I think you can right-off-the-bat switch Florida, Virginia, Indiana and New Hampshire from blue to red (a total of 57) making it roughly 310-ish to 220-ish.
The above post is probably correct, that it would be smart for Obama to forget some states and just make sure he hangs on to PA, OH, WI, maybe a couple others. But if the economy tanks again and he can't win those rust belt states, which is how he won in 2008, he may need some backups. He may have to go down to Florida and try to scare senior citizens after all.