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ANKARA, Turkey — Turkey’s presidential election appeared on Sunday to be headed for a runoff after the incumbent, NAME_1 NAME_2, failed to win a majority of the vote, a result that left the longtime leader struggling to stave off the toughest political challenge of his career.

The outcome of the vote set the stage for a two-week battle between NAME_3 and NAME_4, the opposition leader, to secure victory in a May 28 runoff that may reshape Turkey’s political landscape.

With the unofficial count nearly completed, NAME_3 received 49.4 percent of the vote to NAME_5’s 44.8 percent, according to the state-run NAME_6 news agency.

But both sides claimed to be ahead.

“Although the final results are not in yet, we are leading by far,” NAME_3 told supporters gathered outside his party’s headquarters in Ankara, the capital.
Speaking at his own party’s headquarters, NAME_5 said the vote would express the “nation’s will.” He said, “We are here until each and every vote is counted.’’

The competing claims came early Monday after a nail-biter evening during which each camp accused the other of announcing misleading information. NAME_3 warned the opposition on Twitter against “usurping the national will” and called on his party faithful “not to leave the polling stations, no matter what, until the results are finalized.”

Opposition politicians disputed the preliminary totals reported by NAME_6, saying that their own figures collected d