The decision by the reformist candidate Mohammadreza Aref to withdraw his candidacy - and in effect open the path for the centrist Hassan Rowhani to become the unified candidate of both the centrists and reformists - is an important development in Iranian politics.
With the disqualification of former president and current chair of the Expediency Council Akbar Hashemi Rafsanjani by a vetting body, the Guardian Council, Iran's presidential campaign is opening with many in the country in a state of shock.