Turkish president Recep Tayyip Erdogan on Saturday called for the opposition's local election victory in Istanbul to be declared invalid and the vote re-run, increasing the pressure on the country's electoral authorities.
"Clearly, there were irregularities and corruption," Erdogan said in a speech at a business leaders' meeting.
"If the Supreme Electoral Council could dissipate all this, that would ease the conscience of our fellow citizens," he added.
The electoral body, the YSK, is due to meet on Monday to examine a request by Erdogan's AKP party to cancel the result of the March 31 local elections which the party lost in Istanbul, where the main opposition candidate Ekrem Imamoglu won the mayoral race by a tight margin.
Several partial recounts have so far supported the initial results in both Ankara and Istanbul, with the main opposition CHP party calling Erdogan a "bad loser" willing to do anything to hold on to power in the country's economic capital.
Observers attribute the electoral setbacks to the ruling Justice and Development Party (AKP) to voter discontent over Turkey's ongoing economic troubles.
Refusing to concede the Istanbul result, Erdogan denounced "massive irregularities", and his party accused voting officials of under-reporting votes cast in favour of its candidate.
"My fellow citizens say to me: 'My president, there must be a re-run of this election'," Erdogan said. "Come and let's go before the people and we will accept what the people's wish dictates."