Turkish citizens headed to the polls on Sunday for twin presidential and parliamentary elections that could shape the Turkish political landscape for the upcoming years.

The polls opened at 8 a.m. and will close at 5 p.m. Unofficial results are expected after 9 p.m.

Some 61 million voters are registered to cast their ballots. Around 3.5 million voters living abroad have been called to cast their votes in advance. More than 1.76 million Turks abroad have cast their votes at diplomatic missions and customs gates between April 27 and May 9.

The polls could stretch incumbent President Recep Tayyip Erdogan's rule into a third decade or could set Türkiye, a NATO-member country of 85 million, on a new course.

In Diyarbakir, a city in the mainly Kurdish southeast which was hit by a devastating earthquake in February, some said they had voted for the opposition and others for Erdogan.

"A change is needed for the country," said Nuri Can, 26, who cited Türkiye's economic crisis as the reason for voting for Kilicdaroglu. "After the election there will be an economic crisis at the door again, so I wanted change."

But Hayati Arslan, 51, said he had voted for Erdogan and his AKP. "The country's economic situation is not good but I still believe that Erdogan will fix this situation. Türkiye's prestige abroad has reached a very good point with Erdogan and I want this to continue."

According to pollsters, Erdogan, 69, is facing his toughest test yet during his 20-year rule. Erdogan, founder and leader of the conservative Justice and Development Party (AKP), has been leading the country since he became prime minister in 2003.

There are three presidential candidates, however. Erdogan's chief opponent is Kemal Kilicdaroglu, 74, the leader of the center-left People's Republican Party (CHP), who might have a chance of winning for the first time as he is backed by a bloc of opposition parties, according to surveys. The third candidate Sinan Ogan is appealing for nationalist votes. A fourth presidential contender, Muharrem Ince, withdrew from the race on Thursday. 

If no presidential candidate wins over 50 percent of the vote on Sunday, there will be a runoff vote on May 28.

Voters will also elect a new parliament and its 600 members of parliament, likely a tight race between the People's Alliance comprising Erdogan's conservative AKP and the Nationalist Movement Party (MHP) and others, and Kilicdaroglu's Nation Alliance formed of six opposition parties, including his secularist CHP, established by Türkiye's founder Mustafa Kemal Ataturk.

(With input from agencies)