WHO ARE THE PLAYERS?

Recep Tayyip Erdogan (64) Justice and Development Party (AKP)

In power since 2003, first as prime minister and now as president, Erdogan faces his most serious challenge ever, though opinion polls say he is ahead of his rivals. Once a reformist, Erdogan has taken an authoritarian turn, curtailing free speech and jailing thousands

Muharrem Ince (54)

Republican People's Party A former physics teacher, his rallies have drawn large crowds and opinion polls indicate his popularity has surged. Ince promises to change the Constitution and return Turkey to a parliamentary system

Selahattin Demirtas (45)

Peoples' Democratic Party (HDP) A former co-chairman of the pro-kurdish HDP is currently in jail. However, he has continued to run a campaign from his high-security prison while he fights terror-related charges

Meral Aksener (61) Good Party (IYI party)

She split from the

AKP following a spat with its leader over his support to Erdogan in the referendum to increase presidential powers. She has vowed a swift return to a parliamentary system

Temel Karamollaoglu (77) Felicity Party (SP)

Strongly critical of Erdogan's policies, the former engineer has aligned his party with those of Aksener and Ince, and is likely to back them in the event of a runoff presidential vote against Erdogan