People in Turkey will head to the polls on Sunday to vote in a presidential runoff election.

The contest between the incumbent Recep Tayyip Erdogan and Kemal Kilicdaroglu is expected to be close. Kilicdaroglu is the head of the largest opposition party and the joint candidate of six opposition parties.

Neither of the candidates secured the majority needed to win outright during the first round of voting on May 14.

Erdogan led the race with 49.5 percent of the votes. He has highlighted his achievements as prime minister and president over the past 20 years. Erdogan has also been taking credit for a deal that he helped broker between Russia and Ukraine. The deal enables Ukrainian farm products to be exported via the Black Sea.

Kilicdaroglu won about 44.8 percent of the votes in the first round. He has criticized Erdogan's response to runaway inflation in the country and the plunge in the value of Turkey's currency. He has also accused the president of governing with an iron fist.

A survey conducted by Turkish pollster Konda last weekend showed Erdogan leading Kilicdaroglu by nearly five percentage points. About eight percent of the respondents said they were undecided. Those undecided voters will likely determine the outcome of the election, as the runoff is expected to be close.

The polls will open at 8 a.m. on Sunday local time.