There has been a final push for political support in Istanbul, a day before presidential and parliamentary elections widely viewed as the most crucial in Turkey for decades.
The winner of the presidential vote will gain sweeping new executive powers under a constitutional overhaul backed by incumbent, Recep Tayyip Erdogan.
But with Turkey's economic woes mounting, his AK Party is facing a strong challenge from a revitalised opposition.
His main challenger, Muharram Ince of the secularist Republican People's Party, has been a hit on the campaign trail, drawing huge crowds.
An estimated one million people turned out here in Istanbul's Maltepe district to hear Ince vow to reverse what he sees as Erdogan's authoritarian rule.
Meral Aksener, is the only woman in the race and is the second strongest candidate of the opposition, according to the latest polls.
Selahattin Demirtas is the youngest candidate in the race. The Kurdish human rights lawyer has been kept without charge in a maximum-security prison in Edirne, in northwestern Turkey, for more than 20 months.
Temel Karamollaoglu is fourth in the opposition candidate race, and has said he would support Mr. Ince or Ms. Aksener as the opposition candidate.
Erdogan, who has dominated Turkish politics for a decade and a half, is tipped to win the presidential election but possibly only in a run-off set for early July, opinion polls suggest.