Hamdeen Sabahi is at least partly right. "The Muslim Brotherhood is a minority," he told the Associated Press this week. "They get majority votes because of division within the opposition."
The opposition leader should know - he came in third in Egypt's first free presidential elections in May, failing to qualify for the June run-off that President Mohammed Morsi narrowly won. Now, Mr Sabahi is a vocal opponent of the president, and of the new constitution that appears to have been passed by nearly a two-thirds margin of Egyptian voters.
How to explain that margin after the chaos of the past month? Whether the Muslim Brotherhood and its political arm, the Freedom and Justice Party, represent a minority of Egyptians, as Mr Sabahi claims, remains to be seen. The Brotherhood's nearly 80 years of coordinating social programmes and opposition to the previous authoritarian regimes makes it one of the strongest organising forces in a new Egypt.
Mr Sabahi is undeniably correct, however, that the Brotherhood has also benefited from the lack of a coherent opposition. The umbrella group of the National Salvation Front united opposition to the constitution, but its member groups have accomplished little else. Many Egyptians will have chosen the FJP as a vote for stability.
For the past four weeks, tens of thousands of Egyptians have again been taking to the streets to protest against this new government. Clashes between protesters and riot police are an almost daily occurrence. In a country with a foundering economy - the pound fell to an eight-year low yesterday after a ratings downgrade - interminable protests are not an option.
The opposition cannot keep relying on Tahrir Square to mobilise its supporters. Ahead of parliamentary elections, the many and varied parties have to find common ground, mobilise supporters - and prove their commitment to the political process. That includes getting protests off the streets.
That will be no easy task - the FJP has won three successive times at the ballot box. If the majority of Egyptians chooses the Brotherhood, the country - and its supporters - will have to find an accommodation.
It is far from clear that Mr Morsi and his backers will offer an accommodation in any event. There are many reasons to object to the way this constitution was ramrodded through at the cost of social stability. The results are still questioned because of the low turnout.
But if the FJP has won this round, which appears almost certain, Mr Sabahi and his prospective allies have their work cut out for them. That begins with helping to restore order.