Turkish President Recep Tayyip Erdogan's rival vowed Monday to win a runoff election after almost complete results showed neither candidate had secured the required 50 percent of the vote.

"If our nation says second round, we will absolutely win in the second round," Kemal Kilicdaroglu told reporters. "The will for change in society is higher than 50 percent."

Also Read: Turkey decides Erdogan's future in knife-edge vote

Turkey on Sunday voted in a momentous election that could extend President Recep Tayyip Erdogan's 21-year grip on power or put the mostly Muslim nation on a more secular course.

The presidential and parliamentary ballot has turned into a referendum on Turkey's longest-serving leader and his party.