Ankara. Preliminary, unofficial results from Turkish news agencies showed incumbent President Recep Tayyip Erdogan ahead with 88 percent of ballot boxes counted in a presidential runoff that will decide whether the country’s longtime leader stretches his increasingly authoritarian rule into a third decade.

The state Anadolu news agency showed Erdogan at 53 percent, and his challenger, Kemal Kilicdaroglu, at 47 %.

Meanwhile, the ANKA news agency, close to the opposition, showed the results at 51 percent for Erdogan and Kilicdaroglu at 49 percent.

The outcome could have implications far beyond Ankara. Turkey stands at the crossroads of Europe and Asia, and it plays a key role in NATO.

Erdogan’s government vetoed Sweden’s bid to join NATO and purchased Russian missile-defense systems, which prompted the United States to oust Turkey from a U.S.-led fighter-jet project. But it also helped broker a crucial deal that allowed Ukrainian grain shipments and averted a global food crisis.

The competing news agencies get their data from completed ballot box counts that are gathered by personnel on the field, and are strong in different regions, explaining some of the variation in preliminary data. Turkey’s electoral board sends its own data to political parties throughout the vote count but doesn’t declare official results until days later.

President Recep Tayyip Erdogan, who has been at Turkey’s helm for 20 years, was favored to win a new five-year term in the second-round runoff, after coming just short of outright victory in the first round on May 14.