TURKISH voters will go to the polls tomorrow in a historic double election for the presidency and parliament.

The election represents a gamble by President Recep Tayyip Erdogan, who will emerge either with unparalleled power as executive president or with a bloody nose for over-reaching himself.

The vote is taking place 16 months earlier than scheduled, amid a semi-permanent state of emergency and signs of a declining economy.

Mr Erdogan, the former Istanbul mayor and presidential incumbent, faces challenges from five candidates, principally Muharrem Ince, who was nominated by the leading opposition force, the People’s Republican Party (CHP), and human rights lawyer Selahattin Demirtas of the pro-Kurdish People’s Democratic Party (HDP).

Mr Demirtas has the added disadvantage of having to lead his campaign via social media from jail, where he’s been held in pre-trial detention on alleged terror charges since November 2016.

Apart from the presidency, 600 MPs will be elected to parliament, with eight parties and independent candidates competing for five-year terms.

A recent change to electoral laws permits parties to form alliances, which can assist smaller allied parties to bypass the minimum 10 per cent threshold required for a single party to enter parliament.

Five of the parties are running both individually and as part of two competing alliances.

The social-democratic CHP is joined in alliance by the nationalist Good Party and the small Islamist-leaning Felicity Party, while the HDP has been excluded from the opposition grouping and will have to pass the 10 per cent threshold alone.