Turkey's top electoral board is considering objections Wednesday to the way the country's referendum was run, according to Turkey's semi-official Anadolu news agency.
The Istanbul Bar Association filed a criminal complaint against electoral board head Sadi Guven for "wrongful conduct" and "altering the result of the election".
The referendum on constitutional amendments that would expand the powers of Turkish President Recep Tayyip Erdogan was held in Turkey on Sunday, with 51.4 percent of voters supporting the proposed amendments.
Bulent Tezcan, deputy chairman of the opposition Republican People's Party, or CHP, said the party filed a formal request seeking the referendum's annulment due to voting irregularities.
He went on to warn that calling for street protests is unacceptable. The foreign ministry said foreign monitors lacked objectivity and impartiality.
"Calling people to the street is wrong and is outside the line of legitimacy", Yildirim said, adding, "we expect the main opposition party's leader to act more responsibly". Another petitioner, Fusun Cicekoglu, 61, said, "I will not accept my "no" vote be voided and I will not accept "yes" ballots cast illegally".
On Monday, global election monitors delivered a scathing verdict on the conduct of the referendum.
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World Health Organization regional director for Africa Dr Matshidiso Moeti told the BBC: "The prospect of a malaria vaccine is great".
Global observers charged on 17 April that the referendum campaign was conducted on an "unlevel playing field" and that the vote count was "marred by late procedural changes that removed key safeguards".
Royce said he was troubled by the observers' initial reports of irregularities and would review the full report when released.
The referendum results cement a yearslong effort by Erdogan - who has served as President since 2014, following almost a decade as Prime Minister - to consolidate his position.
The opposition parties' request to completely annul the results will be decided at the national level by the YSK. "No" campaigners claimed they have faced intimidation and threats of violence, while independent monitors say state media slanted coverage in favor of the president.
During an interview with Erin Burnett on CNN's "OutFront", Allen, the former commander of the International Security Assistance Force in Afghanistan and the former special presidential envoy to the Global Coalition to Counter ISIS, said "President Trump can certainly do what he wants to do on this issue".
He rejected accusations that he supported the new powers out of a desire to empower himself rather than improve Turkey's political system.