ISTANBUL, May 26 (Reuters) - President Tayyip Erdogan has defied forecasts of his political demise in Turkey's elections, rallying voters with a potent mix of religious conservatism and nationalism that looks set to propel his rule into a third decade on Sunday. Though he has yet to clinch victory - Erdogan must first beat Kemal Kilicdaroglu in Sunday's runoff - his momentum has only grown since he emerged with a solid lead in the first round on May 14, and analysts fully expect him to win. See here for a complete list of exchanges and delays