(A view shows buildings plastered with Prime Minister Tayyip Erdogan's election campaign posters, as a ferry leaves Eminonu pier in Istanbul June 10, 2011/Murad Sezer)

The last time Turks voted in a general election in 2007, opponents feared the socially conservative ruling party was turning Turkey into an Iran-style Islamic state. With voters on Sunday expected to keep Prime Minister Tayyip Erdogan’s AK Party in office for a third straight term, critics and some analysts now worry about that less but fear that the future course of democracy may be at stake.

A rising power with a vibrant, free economy and a U.S. ally that aspires to join the European Union, Turkey is held up as an example of marrying Islam and democracy and has been an oasis of stability in a region convulsed by “Arab Spring” uprisings. AK has also overseen the most stable and prosperous period of Turkey’s history with market-friendly reforms, and begun membership talks with the EU while opening new markets in Asia, the Middle East and Africa.

( Turkish Prime Minister Tayyip Erdogan's election campaign posters in Istanbul June 10, 2011. The posters read, "Stability proceeds, Turkey grows" and "Turkey is ready, Target is 2023"/Murad Sezer)

But Erdogan, whose party controls the government and parliament and who last year won a referendum to overhaul the judiciary, says if he wins by a big enough margin this time and achieves a “super majority,” he will rewrite Turkey’s constitution.