IZMIR, TURKEY - APRIL 02 : "Yes" and "No" leaflets and billboards prepared for the referendum are seen in Izmir, Turkey prior to the constitutional referendum which comes into prominence with the changes on presidential system on April 2, 2017. Turkish citizens will vote on April 16, 2017 in a referendum on constitutional changes. ( Mahmut Serdar Alakuş - Anadolu Agency )

IZMIR, TURKEY - APRIL 02 : "Yes" billboards prepared for the referendum are seen in Izmir, Turkey prior to the constitutional referendum which comes into prominence with the changes on presidential system on April 2, 2017. Turkish citizens will vote on April 16, 2017 in a referendum on constitutional changes. ( Mahmut Serdar Alakuş - Anadolu Agency )

IZMIR, TURKEY - APRIL 02 : "Yes" and "No" leaflets and billboards prepared for the referendum are seen in Izmir, Turkey prior to the constitutional referendum which comes into prominence with the changes on presidential system on April 2, 2017. Turkish citizens will vote on April 16, 2017 in a referendum on constitutional changes. ( Mahmut Serdar Alakuş - Anadolu Agency )

IZMIR, TURKEY - APRIL 02 : "Yes" and "No" leaflets and billboards prepared for the referendum are seen in Izmir, Turkey prior to the constitutional referendum which comes into prominence with the changes on presidential system on April 2, 2017. Turkish citizens will vote on April 16, 2017 in a referendum on constitutional changes. ( Mahmut Serdar Alakuş - Anadolu Agency )

IZMIR, TURKEY - APRIL 02 : "Yes" and "No" leaflets and billboards prepared for the referendum are seen in Izmir, Turkey prior to the constitutional referendum which comes into prominence with the changes on presidential system on April 2, 2017. Turkish citizens will vote on April 16, 2017 in a referendum on constitutional changes. ( Mahmut Serdar Alakuş - Anadolu Agency )

IZMIR, TURKEY - APRIL 02: People hold the "Yes" leaflets prepared for the referendum to inform citizens in Izmir, Turkey prior to the constitutional referendum which comes into prominence with the changes on presidential system on April 02, 2017 in Izmir, Turkey. Turkish citizens will vote on April 16, 2017 in a referendum on constitutional changes. ( Mahmut Serdar Alakuş - Anadolu Agency )

IZMIR, TURKEY - APRIL 02: People hold the "Yes" leaflets prepared for the referendum to inform citizens in Izmir, Turkey prior to the constitutional referendum which comes into prominence with the changes on presidential system on April 02, 2017 in Izmir, Turkey. Turkish citizens will vote on April 16, 2017 in a referendum on constitutional changes. ( Mahmut Serdar Alakuş - Anadolu Agency )

IZMIR, TURKEY - APRIL 02: "No" stickers and banners prepared for the referendum are seen in Izmir, Turkey prior to the constitutional referendum which comes into prominence with the changes on presidential system on April 02, 2017 in Izmir, Turkey. Turkish citizens will vote on April 16, 2017 in a referendum on constitutional changes. ( Mahmut Serdar Alakuş - Anadolu Agency )

IZMIR, TURKEY - APRIL 02: "Yes" leaflets prepared for the referendum are seen in Izmir, Turkey prior to the constitutional referendum which comes into prominence with the changes on presidential system on April 02, 2017 in Izmir, Turkey. Turkish citizens will vote on April 16, 2017 in a referendum on constitutional changes. ( Mahmut Serdar Alakuş - Anadolu Agency )

IZMIR, TURKEY - APRIL 02: People talk each other in front of the "No" billboard prepared for the referendum in Izmir, Turkey prior to the constitutional referendum which comes into prominence with the changes on presidential system on April 02, 2017 in Izmir, Turkey. Turkish citizens will vote on April 16, 2017 in a referendum on constitutional changes. ( Mahmut Serdar Alakuş - Anadolu Agency )

ISTANBUL, TURKEY - APRIL 3: A "Yes" banner is seen prior to the constitutional referendum which comes into prominence with the changes on presidential system in Istanbul, Turkey on April 3, 2017. Turkish citizens will vote on April 16, 2017 in a referendum on constitutional changes. ( Berk Özkan - Anadolu Agency )

ISTANBUL, TURKEY - APRIL 3: "Yes" banners are seen prior to the constitutional referendum which comes into prominence with the changes on presidential system in Istanbul, Turkey on April 3, 2017. Turkish citizens will vote on April 16, 2017 in a referendum on constitutional changes. ( Berk Özkan - Anadolu Agency )

ISTANBUL, TURKEY - APRIL 3: "Yes" banners are seen prior to the constitutional referendum which comes into prominence with the changes on presidential system in Istanbul, Turkey on April 3, 2017. Turkish citizens will vote on April 16, 2017 in a referendum on constitutional changes. ( Berk Özkan - Anadolu Agency )

ISTANBUL, TURKEY - APRIL 3: "No" banner is seen prior to the constitutional referendum which comes into prominence with the changes on presidential system in Istanbul, Turkey on April 3, 2017. Turkish citizens will vote on April 16, 2017 in a referendum on constitutional changes. ( Berk Özkan - Anadolu Agency )

ISTANBUL, TURKEY - APRIL 3: A man blows up a "No" balloon prior to the constitutional referendum which comes into prominence with the changes on presidential system in Istanbul, Turkey on April 3, 2017. Turkish citizens will vote on April 16, 2017 in a referendum on constitutional changes ( Berk Özkan - Anadolu Agency )

ISTANBUL, TURKEY - APRIL 3: A woman holds "No" balloons prior to the constitutional referendum which comes into prominence with the changes on presidential system in Istanbul, Turkey on April 3, 2017. Turkish citizens will vote on April 16, 2017 in a referendum on constitutional changes. ( Berk Özkan - Anadolu Agency )

ISTANBUL, TURKEY - APRIL 3: People hold "Yes" flags prior to the constitutional referendum which comes into prominence with the changes on presidential system in Istanbul, Turkey on April 3, 2017. Turkish citizens will vote on April 16, 2017 in a referendum on constitutional changes. ( Berk Özkan - Anadolu Agency )

ISTANBUL, TURKEY - APRIL 3: "Yes" banner is seen prior to the constitutional referendum which comes into prominence with the changes on presidential system in Istanbul, Turkey on April 3, 2017. Turkish citizens will vote on April 16, 2017 in a referendum on constitutional changes. ( Berk Özkan - Anadolu Agency )

ANKARA, TURKEY - APRIL 5 : A bus with a "No" sticker on it is seen in Ankara, Turkey prior to the constitutional referendum which comes into prominence with the changes on presidential system on April 5, 2017. Turkish citizens will vote on April 16, 2017 in a referendum on constitutional changes. ( Emin Sansar - Anadolu Agency )

ANKARA, TURKEY - APRIL 5 : A woman wearing a t-shirt reading "Yes" holds a leaflet in Ankara, Turkey prior to the constitutional referendum which comes into prominence with the changes on presidential system on April 5, 2017. Turkish citizens will vote on April 16, 2017 in a referendum on constitutional changes. ( Emin Sansar - Anadolu Agency )

ANKARA, TURKEY - APRIL 5 : A man wearing a t-shirt reading "No" holds a Turkish flag in Ankara, Turkey prior to the constitutional referendum which comes into prominence with the changes on presidential system on April 5, 2017. Turkish citizens will vote on April 16, 2017 in a referendum on constitutional changes. ( Emin Sansar - Anadolu Agency )

ANKARA, TURKEY - APRIL 5 : People hold "Yes" and "No" leaflets in Ankara, Turkey prior to the constitutional referendum which comes into prominence with the changes on presidential system on April 5, 2017. Turkish citizens will vote on April 16, 2017 in a referendum on constitutional changes. ( Emin Sansar - Anadolu Agency )

ANKARA, TURKEY - APRIL 5 : "Yes" and "No" banners are seen in Ankara, Turkey prior to the constitutional referendum which comes into prominence with the changes on presidential system on April 5, 2017. Turkish citizens will vote on April 16, 2017 in a referendum on constitutional changes. ( Emin Sansar - Anadolu Agency )

IZMIR, TURKEY - APRIL 02: People talk each other in front of the "No" billboard prepared for the referendum in Izmir, Turkey prior to the constitutional referendum which comes into prominence with the changes on presidential system on April 02, 2017 in Izmir, Turkey. Turkish citizens will vote on April 16, 2017 in a referendum on constitutional changes. ( Mahmut Serdar Alakuş - Anadolu Agency )