Waiting for Khalifa or Imam Mehdi to do what is already been told is wrong approach.
no doubt that Islam has emphasised alot on the self purification and that should be the goal of all the Muslims on the personal level but this is not a condition for establishment of an Islamic leadership. The rule of Imamat/Khlafat is to guide the ummat after our master Guide Prophet Mohammad passed away. And i think that guidance should be descending and not ascending. And remmember what was said above by a brother that Islam has a greater role to play then just on the personal level ie political.
bro if u think that somehow miracoulously all the Muslim ummah will achieve self purification and then there wont be any bad guys left and when no bad guys left then a JUST leader will be chosen/nominated to fill the leadership vacuum. And since all the people will be SADIQ and AMEEN, they will abide by this khalifa/imam and all shall live happily ever after! bro as much as i would love to see the above happen it wont. Coz u know shaitaan isn't sitting there doing nothing. And no representative of Allah has been able to get the people to agree on the truth. Like sister said in earlier post that even in Prophet Mohammads' time there were munafiqeen within the Islamic circles. So if people who sat, ate, drank, talked with our Prophet did not accept his mission and worked against him, how could you expect today after 1400years 1.6Billion Muslims to somehow miracoulously embrace it and agree on it.
In Quran Sura Nissa verse 59, obedience to the "Prople in charge/authority" is made obligatory and i find it hard to believe that Quran will not contain any guidance as to how this authority is established. On one hand we say Quran is a complete book and contains everything from what to eat, who to marry, what to wear, how to engage in sexual activities etc and on the other hand we say Quran does not say anything about something as fundamentaly important as chosing a leader! Some have said that Allah subhana wa ta'lah has left that for us to decide. Well if this was the case then Quran would have said so and put forward clear rules like it has done for the other commands. I believe that Quran does have EVERYTHING in it and we just have to look harder. May be we have gone blind and may be it will take Imam Mahdi to open our eyes! May Allah hasten his appearence, Insha Allah........in the meantime we must strive to purify ourselves, ask Allah and his messenger for continous guidance so we could recognise the right from wrong and support the forces who are fighting for the truth.