The real battle for Egypt is against endemic poverty and the corruption of civil life from the highest levels of the state and the judiciary all the way down to the cop on the beat.
The most important fact about Egyptian politics is that none of the parties now contending for power can win either of these fights. Anyone who wins power will bleed off popular support before too long, as their inevitable failures become more apparent.
This suggests the problem in Egypt is not so much how a democratic government with a mandate can survive but how a government, elected or not, can maintain order when it loses its popular legitimacy. That is a question of organization and force, ultimately, and it is why the army has remained the most powerful force in the country since the overthrow of the last king.
For the Muslim Brotherhood the question is whether the power of the mosque and of preaching, supplemented by a street organization and a political get-out-the-vote machine, can provide order and stability even as, on issue after issue, the Brotherhood fails to deliver on the economic promises it has made.
Probably one reason the Brotherhood leadership wants a fast referendum on the constitution is a sense that time is not on its side. The economy is not going to perform miracles. The miasma of corruption and the oppression of ordinary people by even the lowliest minions of the state (think of the Egyptian equivalent of the surly DMV worker) will not end. Certain Brotherhood leaders will quickly become rich. Many people with no religious convictions will join the movement to latch on to the patronage networks of the state.
And the poor will seethe and fume…
Democratic or not, radical or not, the Brotherhood has to move fast to consolidate its position before the prize it has grasped at for sixty years dribbles out of its grasp. And because of the nature of Egyptian society and the limits of its economic options, even if power is obtained democratically, it probably cannot be held in that way—by anybody.