ISTANBUL (AP) ― Turks were voting in their first direct presidential election Sunday, a watershed event in the 91-year history of a country where the president was previously elected by Parliament.

Prime Minister Recep Tayyip Erdogan, who has dominated Turkey’s politics for the past decade, is the strong front-runner to replace the incumbent, Abdullah Gul, for a five-year term.

Erdogan, who is serving his third term as prime minister, has been a polarizing figure in Turkey. Fervently supported by many as a man of the people who has led the country through a period of economic prosperity, he is viewed by critics as an increasingly autocratic leader bent on concentrating power and trying to impose his religious and conservative views on a country founded on strong secular traditions. Party rules barred him from serving another term as prime minister.

Erdogan is running against two other candidates. His main challenger is Ekmeleddin Ihsanoglu, a 70-year-old academic and former chief of the Organization of Islamic Cooperation who is backed by several opposition parties, including the two main ones: a pro-secular party and a nationalist one. The third candidate is 41-year-old Kurdish politician Selahattin Demirtas, a rising star on the minority Kurdish political scene.

Some 53 million people are eligible to vote; a candidate needs an absolute majority for victory. If none wins enough ballots, a runoff between the top two will be held on Aug. 24.

Erdogan, whose Justice and Development Party, or AKP, won local elections in March with about 43 percent of the vote, is widely expected to be elected, although it is unclear if he can avoid a runoff.

“The key criteria, or litmus test, will be what percentage of the votes does Prime Minister Erdogan secure in the first round of presidential elections,” said Fadi Hakura, an associate fellow at the Chatham House think tank in London.

“I think the key figure here will be 45 percent.”

A percentage below what his party won in local elections could indicate Erdogan’s popularity is starting to wane, he said.

After a bitter and divisive pre-election campaign, Erdogan sounded a more conciliatory, unifying note in his final campaign speech Saturday.

“This country of 77 million is our country, there is no discrimination,” he said. “We own this country all together.”

Erdogan‘s critics have pointed to a vastly one-sided election campaign dominated by the prime minister. He has been criticized for using the resources of his office to monopolize media coverage and crisscross the country on the campaign trail. He has denied any inappropriate use of state assets.

Although largely a ceremonial role, Erdogan has vowed to transform the presidency into a powerful position -- something his detractors point to as proof he is bent on a power grab.

He has said he will activate the post’s rarely used dormant powers, including the ability to call Parliament and summon and preside over cabinet meetings. The powers are a legacy of a 1980 military coup.

Ihsanoglu, whose campaign focused on a message of unity, disagrees with changing the role of the president.

“I am against the accumulation of power in one hand. I think that would lead to more centralized government and an unwelcomed totalitarian regime that Turks don‘t want to have,” he said.