Ankara, May 17 : Turkish President Recep Tayyip Erdogan has vowed to win "a greater victory" in the runoff presidential election on May 28. "Now is the time to crown the success we achieved on May 14 with a greater victory," Erdogan said on Twitter on Tuesday. "We have already started working for the May 28 election," he added. Turkey's election watchdog announced on Monday a runoff is scheduled for May 28 as no presidential candidate secured more than 50 per cent of vote in the initial round, Xinhua news agency reported. Erdogan led with 49.51 per cent, his rival Kemal Kilicdaroglu gained 44.88 per cent, and Sinan Ogan, the third candidate, had 5.17 per cent, according to Ahmet Yener, head of the Supreme Election Board. After the second round of polls between Erdogan and Kilicdaroglu on May 28, the one who secures more votes will be the next Turkish President, according to Turkish law. /IANS