Updated

Few men can claim to have dominated politics in Turkey — or polarized his people — as much as Recep Tayyip Erdogan, the 63-year-old president who has urged his nation to approve reforms that will greatly expand his powers.

Rising from humble origins to take the helm of the country's government in 2003 as prime minister, Erdogan quickly attracted a fervent following from his support base, but became feared and hated by many who saw him as an increasingly autocratic, power-hungry leader seeking to erode Turkey's secular traditions by imposing his conservative, religious views.

On Sunday, voters decide whether to approve sweeping constitutional changes that will change the country's system of government from parliamentary to presidential, and grant their president the authority to appoint ministers and government officials, appoint half the members of the country's highest judicial body, issue decrees and declare states of emergency. The changes, one of the most radical political reforms since the Turkish republic was established in 1923, could see Erdogan remain in power until 2029.

Erdogan served three consecutive terms as prime minister as head of his Islamic-rooted Justice and Development Party, before becoming Turkey's first directly-elected president in 2014.

Supporters found in him a man who gave a voice to the working- and middle-class religious Turks who had long felt marginalized by the country's Western-leaning elite. He was seen to have ushered in a period of stability and economic prosperity, building roads, schools, hospitals and airports in previously neglected areas, transforming hitherto backwaters.

"He's a real leadership figure because he is not a politician that comes from the outside. He comes from the street," said Birol Akgun, an academic at the international relations department of Ankara's Yildirim Beyazit University. "He knows the language of the street. He has 40 years of political experience and is very strong in practical terms."

But with each election win, Erdogan grew more powerful, and, his critics say, more authoritarian.

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. After surviving an attempted coup last July, Erdogan launched a broad, sweeping crackdown against followers of his former ally, Islamic cleric Fethullah Gulen, who lives in the United States.

The crackdown saw roughly 100,000 people lose their jobs, including judges, lawyers, teachers, journalists, military officers and police. More than 40,000 people have been arrested and jailed, including pro-Kurdish lawmakers. Media outlets are stifled, hundreds of non-governmental organizations and news outlets have been shut down, as have many businesses, from schools to fertility clinics.

Erdogan has also blasted European countries, accusing the Netherlands of Germany of being Nazis after authorities there refused to allow Turkish ministers to hold rallies to woo expatriate voters for the referendum.

His critics fear that if the "yes" vote prevails in Sunday's referendum, Erdogan will have cemented his grip on power with scant chance of checks and balances, and practically no room for opposition or dissent.

"He says he'll decide everything. One person will determine national security policies according to the constitutional changes. Why one person? What if he makes a mistake, what if he is deceived, what if he is bought?" said Kemal Kilicdaroglu, head of the main opposition Republican People's Party, during a "no" rally in Ankara Saturday.

"Surrendering the Republic of Turkey to one person is a heavy sin. It's very heavy. Can there be a state without rights and justice?"

As prime minister, Erdogan also garnered support from within the Kurdish minority — estimated at about 20 percent of Turkey's roughly 80 million people — after easing restrictions on the right to be educated in Kurdish and to give children Kurdish names. He oversaw a fragile ceasefire in the fight between the state and Kurdish rebels in the country's southeast, a conflict that has claimed an estimated 40,000 lives since 1984.

But the ceasefire collapsed in 2015, and about 2,000 people have died since then, including nearly 800 members of the security forces. With renewed fighting in the southeastern predominantly Kurdish areas, it is unclear whether he would still enjoy support from among the minority.

Erdogan has promised the new presidential system will herald a period of stability and prosperity for Turkey, a country that has suffered several coups in the past few decades.

"He is a harsh leader in character," said Akgun, the academic, who also used to head a pro-government NGO. "But in Turkey, a country that has so many problems, in societies like ours, the image of strong leadership is necessary to command both fear and respect and trust in society."