The Justice and Development Party, or AKP, filed its "extraordinary objection" to the March 31 election results for Istanbul metropolitan mayor with Turkey's electoral board. Citing alleged irregularities, the party previously pushed for a recount of votes, and that process is still underway in one Istanbul district.
President Recep Tayyip Erdogan's AKP and its nationalist ally won a majority of local election votes across Turkey but lost in the capital, Ankara. In Istanbul, unofficial contested results give the main opposition party's mayoral candidate, Ekrem Imamoglu, a 13,827-vote lead over AKP candidate Binali Yildirim.
That difference has dropped from some 25,000 votes with the partial recount.
Speaking to reporters after filing the objection, Ali Ihsan Yavuz, the AKP's deputy chairman, said their previous request for a total recount was not granted. He asserted that had all votes been recounted "this election would have resulted in our benefit."
He said the elections were marred by "organized irregularity" and submitted three suitcases of documents purportedly documenting fraud to the electoral board.
The board is expected to rule on the ruling party's request after all recounts are complete. If it accepts the AKP's objection, Istanbul could repeat the election on June 2.
Both Ankara and Istanbul had been held by Erdogan's conservative, religious-based party and its predecessor for 25 years.
Istanbul, with its 15 million residents and strategic location straddling Europe and Asia, is Turkey's financial and cultural heart. It made up 31% of Turkey's GDP of $851 billion in 2017 and draws millions of tourists.
The Istanbul metropolitan mayorship and its subsidiaries had a total budget of $8.8 billion last year. The municipality has awarded lucrative contracts to businesses close to the government over the years and offers huge financial resources and employment opportunities.
Erdogan's rise to power began as Istanbul mayor in 1994 and he has repeated numerous times in pre-election rallies: "Whoever wins Istanbul, wins Turkey" and "Whoever loses Istanbul, loses Turkey."
On Monday, ruling party candidate Yildirim said the elections were tarnished with "irregularities, mistakes, stains, vote thievery, among others."
Prior to the elections, his party had said the safety of ballot boxes was guaranteed.
Opposition candidate Imamoglu has demanded that he be given the mandate to begin his job as Istanbul mayor. His party has said the AKP's objections lacked credible evidence and asserted that the ruling party aimed to drag out the process to push for new elections.
The AKP still holds 24 of Istanbul's 39 municipal districts.