A look at the candidates in Turkey's presidential elections

Turkey is heading toward presidential and parliamentary elections on Sunday. President Recep Tayyip has dominated Turkish politics over the past two decades. But he has never appeared more vulnerable to an opposition challenge. The president has tightened his grip on power and steered the country toward increasingly authoritarian rule. But Erdogan is trailing in opinion polls behind Kemal Kilicdaroglu. He is the joint candidate of a united opposition that has vowed to restore democracy.