Our criteria is what makes it so unlikely that it will succeed.
The Iraqi people need to determine what kind of gov't they will have because they sure as hell don't trust us to do it for them. And isn't that what democracy is about? Deciding for themselves?
We won't accept a Shi'ite state based on Shariah law, we won't accept a gov't formed by the other muslim sects based on their ideological view of shariah either. The funny thing is that although Saddam was a tyrant, mass murderer and all around evil dude, his secular gov't was probably the closest those folks have ever come to a "democracy". Without his secular gov't they are likely to start more inter-religeous warfare as they stake their claim to the state.