By Eliza Mackintosh, Nadeen Ebrahim, Tamara Qiblawi and Tara Subramaniam, CNN
From CNN's Eliza Mackintosh in London
President Recep Tayyip ruling Justice and Development (AK) Party has tweeted a video showing scenes of crowds outside their headquarters in Turkey's capital Ankara with the caption: "The balcony is ready. The nation is waiting for its leader."
Erdogan is expected to make a speech there shortly.
From CNN's Hande Atay Alam in Atlanta and Isil Sariyuce in Istanbul
Opposition candidate Kemal Kilicdaroglu accused President Recep Tayyip Erdogan's ruling Justice and Development (AK) Party of demanding recounts and delaying results in opposition strongholds, including in Ankara and Istanbul.
"My dear nation, they are blocking the system with repeated objections at ballots where we have higher votes. For example, there are persistent objections at 300 ballots in Ankara and 783 ballots in Istanbul. There is a ballot with six, and another with 11 objections," he told reporters in a statement at his party headquarters in Ankara.
What you are blocking now is the willpower of Turkey."
Kilicdaroglu called on Erdogan to stop dealing in "perception management," adding that the opposition will not allow the vote to be a "fait accompli."
"This is a serious matter. Let the votes come in and the result to be known as soon as possible. The country can no longer tolerate uncertainty. Do not be afraid of the nation’s will," he said.
He also urged election officials to act responsibly, and not let the process be stalled.
"I repeat: Do not block this nation’s will. I would like to call on the democracy workers in the field. Do not leave the ballots and election councils. We are here until every vote has been counted," he said.
From CNN's Yusuf Gezer in Istanbul and Hande Atay Alam in Atlanta
The opposition mayor of Ankara, Mansur Yavas, has said he expects Kemal Kilicdaroglu to finish ahead of President Recep Tayyip Erdogan.
"According to our data, the ratio of officially signed ballot reports is at 69.67%. Proportionally, Kemal Kilicdaroglu's vote is 47.7% and Recep Tayyip Erdogan's vote is at 45.8%," Yavas, a senior member of Kilicdaroglu's opposition Republican People's Party (CHP), told a news conference in the party headquarters in Ankara. "We will wait for the result, it is our duty to seek justice for even one vote."
It is highly likely that Mr. Kilicdaroglu will finish this round first, and there is a high probability of qualifying for the second round," he added.
Yavas will serve as vice president if Kilicdaroglu's six-party Nation Alliance wins.
Turkey's electoral council, which will announce the final vote, has said that 71.64% of ballots have been counted in the country, and 18.67% from those who voted abroad. The council's chairman, Ahmet Yener, said there was "no disruption or delay at the moment."
From CNN's Tamara Qiblawi and Gul Tuysuz in Istanbul
The music came to an abrupt halt at a rally outside the Justice and Development Party (AK Party) headquarters in Istanbul on Sunday evening, as soon as President Recep Tayyip Erdogan's tally slipped below the 50% threshold needed to avoid a runoff.
AK Party supporters pointed at the screen displaying the preliminary results reported by state-run Anadolu news agency. A hushed silence fell over the crowd that just hours earlier was jubilant over early reports that showed Erdogan with a comfortable lead.
We’re not used to this. We’re used to winning the first round,” said Umran Ozdwmie, a 38-year-old who works in cleaning services. “Tomorrow morning when I wake up I wanna see Erdogan still leading us.”
Still the mood was defiant. "We’re come back with even more strength in the second round," said Nuray Ekici, a 31-year-old teacher. "We will never abandon him."
Another man, Ismail Boyaci, 53, said, "Our mood may have changed but Erdogan’s leadership won’t change. We will continue to stand upright."
From CNN's Gokce Katkici and Hande Atay Alam
Ahmet Yener, chairman of Turkey's Supreme Election Council, which will announce the final figures, has said that it has so far entered just over 47% of domestic votes cast in the election and 12.6% of votes from abroad into its system.
During a statement outside the council's headquarters he also rejected allegations from the opposition that it was delaying publishing results.
At this moment, there is no disruption or delay in the data entry undertaken by the Supreme Election Council," he said, adding that the electoral board's data is being shared with political parties "instantaneously."
"The results coming from polling stations are sent to District Election Councils and from there to Provincial Election Councils. This is how the data is entered into the system," he added.
That could mean there is still some time before we get an official result.
From CNN's Tamara Qiblawi and Yusuf Gezer in Istanbul
The gap between the two leading presidential candidates is continuing to narrow as more votes from Turkey's big cities -- which tend to favor opposition candidate Kemal Kilicdaroglu -- pour in.
State news agency Anadolu is reporting that President Recep Tayyip Erdogan's vote has dropped to 49.86% -- below the 50% needed to avoid a runoff -- ahead of Kilicdaroglu's 44.38%, with 90% of votes counted.
As the numbers shifted on screens at the AK Party headquarters in Istanbul, the music stopped and the mood darkened.
Soli Ozel, professor of international relations at Kadir Has University in Istanbul, said the race looked likely to go to a runoff
"Over 60% Turkey's population live in 11 cities. 20% -- thereabouts 18 to 19% of Turkey's population live in Istanbul. Istanbul is a very contested city which the opposition actually won back in 2019," Ozel told CNN.
"So, we are in the clouds, if you will. But it does look, like I must say, that we will have to go to a second round in the presidential since the parliamentary election is a one-round election."
From CNN's Yusuf Gezer in Istanbul and Hande Atay Alam
Opposition candidate Kemal Kilicdaroglu has posted a tweet suggesting that President Recep Tayyip Erdogan's vote share, which started the night at 60%, has now dropped to below 50%.
He urged the country's electoral board, the Supreme Election Council, to stay alert and stick by their posts to provide data entry throughout the evening.
"The fiction which started at 60 percent has now dropped below 50. Ballot observers and election board officials should never leave their places. We will not sleep tonight, my people. I warn the Supreme Election Council, you have to provide data entry in the provinces,” he said.
From CNN's Yusuf Gezer in Istanbul and Hande Atay Alam in Atlanta
Turkish President Recep Tayyip Erdogan asked his supporters on Sunday "to stay at the ballot boxes, no matter what until the results are officially finalized."
"The fact that the 14 May elections took place in the form of a great feast of democracy with peace and quiet is an expression of the democratic maturity of our Turkey," Erdogan said on Twitter.
"I congratulate all my citizens who voted in the name of democracy and took part in the election work, and I express my gratitude to each and every one of them," he added.
From CNN's Isil Sariyuce in Istanbul
The third presidential candidate, Sinan Ogan, an ultra-nationalist who was polling in the single digits, said on Sunday night that he believed the race was likely to go to a runoff.
We see a high probability that the elections will go to the second round," Ogan said on Twitter.
"Turkish nationalists and Kemalists are the key to this election," he said. "Those who attacked us in the last two days after Muharrem Ince was forced out of the elections with various pressures, accused us unjustly and attempted to lynch us should have a lot of lessons to be learned from this political picture!" Ogan was referring to Muharrem Ince, who pulled out of the race on Thursday after what he called a "slander campaign" against him.
With about 85% of ballots counted, Ogan, who is an ally of President Recep Tayyip Erdogan, had only about 5% of the vote, according to preliminary results reported by state-run news agency Anadolu. That support could make Ogan a potential kingmaker in the runoff.