At least not without making it more glaringly obvious than ever before. By that I mean there are too many people aware, damn the polls, that Obama is more popular than Romney by far too much.
It wouldn't be an academic thing like Ohio where everything could be excused away to people that either didn't care or didn't want to know. No, it would be a 'gut' thing where people would be unwilling to accept the weak excuses.
Imagine every single black/AA group, labor union, and teacher's union suddenly jumping into the election fraud issue.
That' would be the consequence of stealing it this time.... at the very least.