Bush went to harvard busuiness school yet they still leveled the charge that he was stupid. Don't forget, both of bush's opponents had worse GPA's than he did. It doesnt' matter who we throw up, there always an idiot. Ever since ike. The only republican who wasn't an idiot was Nixon, but thats b/c the democrats couldn't accuse nixon of being 'tricky dick' and a moron at the same time.
(1) Harvard Law school is much, much harder to enter than Harvard Business School, especially circa 1973 which pre-dated the MBA's late popularity (e.g. Bush applied to UT Law School, but was rejected). Harvard Law is absolute immunity against a stupid charge.
(2) Romney being so articulate is testimony enough to his smarts. An idiot accusation would be risible.
They will have to find another line of attack than intelligence, because it won't stick. They will likely use his religion, because they will have little else to use.