A steady stream of voters arrived at polling stations in Sisli, a middle-class area that is a stronghold of the secularist Republican People’s Party (CHP), shortly after polls opened at 8.00am.
Most voters ready to speak to the media had cast their ballot for Ekmeleddin Ihsanoglu, the independent supported by the CHP, citing his honesty and his academic qualifications as reasons for backing him.
But not many were enthusiastic.
Ihsanoglu was secretary general of the Organisation of Islamic Cooperation until he decided to stand and some secularists find him a strange choice for their party to support.
“His past is more Islamic thoughts and I am not the right for that thinking,” commented Canzu, a finance worker, adding that she doubted he would stand up for the secular values of modern Turkey’s founder, Mustafa Kemal Ataturk.
In Eyup, a more socially mixed and politically divided area, Ihsanoglou voter Sacettin, a jeweller, found the candidate’s campaign had been lacklustre but blamed the parties that had endorsed him.
“I think that the parties that support him should have been campaigning and it seemed as if he was alone,” he commented.
But he turned out to vote anyway, afraid that Erdogan’s election would mean “fascism and dictatorship”.
Sacettin seemed to be in a minority in Eyup, however.
Protective of their right to a secret ballot or discouraged by the men hovering and listening to people talking to the media, many voters declined to comment.
But a number were far from shy of saying that they had voted for Erdogan.
It’s obvious, we have a leader and we vote for him,” said public employee Erdal. “We love him and so I voted for him.”
“He is a world leader, he cares for Muslims,” declared Mustafa a recent graduate.
The run-down Okmeydani neighbourhood is home to members of Turkey’s minorities – Kurds, members of the Alevi sect, recent immigrants from central Asia and Africa.
Here the police are more aggressive, chasing me off the premises of one school where voting is taking place.
Ihsanoglu has supporters among the Alevi, who feel that Erdogan has stirred up Sunni Muslims against them, while many Kurds back left-winger Selhettin Demirtas.
His party, the People’s Democracy Party (HDP), has a stall manned by volunteers, mostly young although housewife Maryam must be twice the age of her coworkers.
“I am here for peace and brotherhood in this country,” she says in Kurdish - she does not speak Turkish.
They are not here to hand out leaflets, of which none are in evidence, but to give advice, Maryam explains.
That doesn’t stop plain-clothes police arriving in an armoured vehicle as the interview is taking place, demanding the identity papers of all the activists and telling them they must pack up their stall.
“The police said they were Kurdish too,” HDP member Aytan says afterwards. “They were talking the Kurdish language with us. They sell their honour in working for the state. We have advice for such people, ‘Police sell simit (cakes) and live honourably.’ ”
See RFI English’s Facebook page for photos from polling day in Istanbul