Blake Zeff thinks not:
For better or worse, Obama is a professional politician, and always has been. This means he plays by similar rules and playbooks as other people in his line of business. Which means that his use of these same standard tools this time around is neither a new part of his arsenal, nor does it represent a threat to his brand, which managed to survive a heated 2008 campaign which has only been cemented further during the subsequent four years.
Josh Green defends the nastiness:
It may not be pretty, but the fact is that pummeling the opposing party into chastened submission has become the only way to settle significant policy disagreements. Romney’s choice of Ryan will nationalize the election around the most significant ones of all—not just taxes and entitlement reform, but the whole nature of the relationship between government and its citizens. The campaign was always going to be brutal and nasty. Now it will be brutal, nasty, and meaningful.