Romney spent $17M in ads in Florida? I another RCP headline says that turnout was down by 200K?
Why? Do the freaking math. That much negativity doesn't just disappear over night - it's not going to be all forgotten come November. This is irreparable damage being done to the Brand, as Sarah Palin says. Say what you like about the lady, but she's got keen political instincts. Far more of her candidates won in 2010 than lost.
Had Romney NOT run all the negative ads in Iowa, and basically turned his cannons on his won side, I'd be far more inclined to back him in the Fall. At this point, the best thing he can do to help the party is leave the race.