This vast, sprawling city is in the grip of election fever, caught up in a boisterous and tense clash of two cultures whose outcome will shape the future of Turkey and resonate beyond the borders of a pivotal country straddling Europe, the Middle East, and the Caucasus.

Virtually every avenue and square is draped in the bunting, posters, and flags of Turkish politics. Campaign lorries power through the traffic-clogged streets, blasting out throbbing Balkan techno music. Boats come paddling up the Golden Horn and motor launches hare across the Bosphorus, peddling political parties and competing to command the attention of voters.

The red and white of the big-city bureaucratic elites who fondly imagine they have a congenital right to rule Turkey are being drowned in a sea of blue, orange and white, the colours of the ascendant new force — the successful nouveaux riches and religious Muslim conservatives from the provinces who stand poised to claim a historic second term victory in general elections on Sunday.

Some see the ballot as a battle between Islam and secularism, others as a referendum on the prime minister, Recep Tayyip Erdogan. Or a contest between competing visions of Turkey — an open, more confident, more democratic place or an isolated Turkey locked in a siege mentality that sees the outside world as conspiring against it.

“This is a poll between those who want more democracy and those who want less,” says E Bagis, an adviser to the prime minister. Pinar Korzay, by contrast, thinks democracy is a luxury that such an unruly country can ill afford. The Istanbul woman, like many Turks, prizes the country’s powerful generals over its politicians.