^^^ Well, the people were on the street long before Mousavi and Karroubi made any claims that could even be interpreted as vote rigging. In fact, vote rigging was not their platform at all - it was the people's platform and they were already clashing with NE saying where's my vote. Don't you remember they requested a recount?! Why would you request a recount when you know the vote was rigged and the same people would be announcing the results?!
And to suggest that their mere candidacy did more for the revolution and led to the street protests would take a serious stretch of the imagination. I accept it as a valid perspective on the situation, but definitely not as a fact. But IMHO this thing was in the making long before the election, no matter who the candidates were. Mousavi was the excuse, not the means to the uprising.
The fact is that Mousavi and Karroubi played within the system before the elections and after the elections and their entire platform, based on their news releases was to save the system of VF, that's an undeniable fact based on their own words - not interpreting their intentions.