Will Turkey Increase Erdogan's Power?

The polls show it is a very tight race with the yes and no campaigns neck and neck.

The 18 constitutional amendments being voted upon in a simple "yes" or "no" vote also would weaken Turkey's parliament, eliminate the post of prime minister, and give the president more control over the judiciary.

Two people were killed as clashes erupted early into voting in Diyarbakir province, with Turkish media reporting that a quarrel between two families over political differences sparked the violence. Still, it would cement his hold on the country's governance.

They would cement Erdogan's grip on a country whose divisions have deepened since a failed coup attempt last July that ended with the deaths of more than 250 people and led to the imposition of a fierce crackdown on dissent.

"The presidential system, according to unofficial results, has been confirmed with a "Yes" vote", Yildirim told supporters from the balcony of the headquarters of the Justice and Development Party (AKP) in Ankara. "A new page has opened in our democratic history with this vote".

But he urged people not to succumb to "lethargy" in voting, saying "the stronger result the better".

"Because we must make an out-of-the-ordinary choice in order to attain the level of modern civilisations envisaged by the hero Mustafa Kemal", the president said, referring to modern Turkey's founder Mustafa Kemal Ataturk.

"Our data indicates a manipulation in the range of 3 to 4 percent", the party said on its Twitter account.

What Turkish citizens do today at the referendum on the presidential system will decide not just the nation's systemic fate but also rewrite its equations with the European Union. But the board changed course after voting was under way, saying it would accept unstamped ballots "unless they are proven to have been brought from outside".

Around 55 million people are eligible to vote.

Turks are now voting in a hotly contested referendum that could place extraordinary powers in the hands of President Tayyip Erdogan, heralding the most radical change to the country's political system in its modern history.

If approved in the referendum, the constitutional changes take effect with the next general elections, scheduled for 2019.

The changes doing away with Turkey's parliamentary system of government constitute one of the most radical political reforms since the Turkish republic was established in 1923.

Bodyguards with automatic weapons stood guard outside the polling station as the president and his wife Emine Erdogan cast their ballots.

The ballots themselves do not include the referendum question.

He described the new system as "a bus with no brakes and whose destination is unknown".

Beyond changing the government system, the vote could also have even wider implications for the key North Atlantic Treaty Organisation member, which for the last half-century has set its sights on joining the European Union.

FILE - In this Saturday, April 15, 2017 photo, Turkey's President Recep Tayyip Erdogan talks to supporters during the last rally ahead of Sunday's referendum, in Istanbul.

"Yes, yes, yes! Our leader is the gift of God to us", said Mualla Sengul. We will always support him. "He's governing so well".

Erdogan first came to power in 2003 as prime minister and served in that role until becoming Turkey's first directly elected president in 2014.

As we count down towards the key vote, one thing is clear: Whichever side claims victory on Sunday, things are not going to be the same in this country, strategically located between three continents.

Mr Aksunger said: "Since this morning, we have determined some 2.5 million problematic votes".

Erdogan blames Gulen, who lives in the United States, and his supporters for plotting the coup, an allegation Gulen has denied.

His election campaigns have been forceful and bitter, with Erdogan lashing out at his opponents, accusing them of endangering the country and even supporting terrorism.