Turkey's double election is about much more than who runs the country.
Turks will vote on Sunday to elect a president and a parliament.
But their vote will also be about how their country is run.
These would give the president the power to rule by decree, unilaterally call new double elections, appoint some senior judges and prosecutors as well as heading a political party in parliament.
All his opponents say they will reverse the changes, which they claim give too much power to one man.