President Recep Tayyip Erdoğan asked Saturday his followers in Istanbul to support the constitutional change in an upcoming referendum.

Speaking at the opening ceremony of the extension of Kadıköy – Kartal metro line in Istanbul's Pendik district, Recep Tayyip Erdoğan said: "I believe that you will walk to the future by working day and night in this campaign for the referendum."

Turkish parliament voted in favor a new 18-article constitutional amendment bill early Saturday after nearly two weeks of acrimonious debate. Out of the total 550 deputies, 339 voted in favor and 142 voted against the bill, falling short of two-thirds majority required for constitutional amendments but passing the 330 threshold to take the amendments before public.

A referendum is expected to be held early April following Erdoğan's approval in the coming days.

"Now I hope the nation will make a real decision," he said.

Proposed changes to the constitution require a simple majority in the referendum. Replacing Turkey's current parliamentary system with a presidential one is the question expected to be submitted to the electorate.

Erdoğan and his supporters have argued that Turkey needs a strong presidency to avoid weak governance and allow the country to successfully tackle a number of challenges, including terror attacks from Daesh, the PKK and the Gülenist Terror Group (FETÖ).

Opponents argue it will weaken democratic checks and lead to increased authoritarianism.