If he has lost his majority in Parliament, he will be using its new, enhanced powers from a weaker popular base. Parliamentarians could be emboldened to defy Erdogan, especially if the economy continues to dip.
Like a generous sultan, Erdogan gave a sop to parliamentarians when he devised the new constitution by giving them the right to impeach the executive president, despite his vast powers over government, the courts and so on. He assumed his party would dominate Parliament, but not any more.
With allegations of corruption swirling around key family members, and charges of abuse of power against him, an Erdogan victory could be reversed by the very constitution that he intended to cement his hold on power for the next decade.
Westerners will probably rejoice at Erdogan's hollow victory, but his opponents are not happy that the European Union and United States supported for him for so long.
Ironically, as Erdogan has veered away from his Nato partners, to embrace Russia and Iran, his domestic rivals have also been calling for an end to Nato's anti-Assad line. Of course, Turkey houses huge numbers of refugees from Syria. Erdogan's failure to resolve the Syrian issue was one of his rivals' most popular charges against him.
Sadly, although Turks are bitterly divided at home, they have voted for politicians united only by being disillusioned with the country's traditional Western partners.
Poll position
• According to unofficial results, Erdogan garnered 52.5 per cent of the presidential vote, while his ruling Justice and Development Party, or AKP, won 42.5 per cent of the parliamentary vote
• Erdogan's closest contender, Muharrem Ince of the secular opposition Republican People's Party, won 30.7 per cent support
• Erdogan's AKP fell short of winning a parliamentary majority but a better-than-expected performance by its nationalist ally should allow the party to control the 600-seat legislature
• Mark Almond is director of the Crisis Research Institute, Oxford.