Turkey on Sunday votes in a pivotal election that could extend President Recep Tayyip Erdogan’s 20-year grip on power or put the mostly Muslim nation on a more secular course.

The presidential ballot has turned into a referendum on Turkey’s longest-serving leader and his Islamic-rooted party. It is also the toughest of more than a dozen that Erdogan has confronted – one that polls suggest the 69-year-old might lose.

The 74-year-old secular opposition leader Kemal Kilicdaroglu is within touching distance of breaking the 50-percent threshold needed to win in the first round. If either of the candidates fail to get more than 50 percent of the vote there will be a runoff election on May 28. Voters will also elect a new 600-seat parliament.