One of the world’s longest serving leaders is looking to extend his iron fisted rule, running another tightly controlled election with no tangible competition as he prepares a possible power succession for his son.

Cambodia’s Prime Minister Hun Sen, 70, has been in power since 1985 – only the leaders of Cameroon and Equatorial Guinea, both also authoritarians, have held office longer.

Voters in the Southeast Asian nation head to the polls on Sunday for the country’s seventh general election but observers predict few surprises.

Following weeks of campaigning and crackdowns on opposition figures, Hun Sen’s ruling Cambodian People’s Party (CPP) is all but running unopposed.

“Like all dictators, Hun Sen will never give up his power,” said Cambodian politician Mu Sochua, who once served as the country’s Minister of Women and Veterans’ Affairs and has since fled overseas.

“The July 23 election is just a day for Hun Sen to impose (his choices) onto the Cambodian people,” she said. “His ruthless policies and practices of eliminating political opponents and critics … is all to protect his power and to transfer it to his eldest son during the late stage of his career.”

Cambodia, a country of 16.5 million people, is renowned for its stunning Angkor temples but also its tumultuous recent history when the Khmer Rouge regime unleashed a genocide on its own people, an event which left families with inter-generational trauma while poverty and corruption remain deep rooted.

A former Khmer Rouge commander who switched sides, Hun Sen has ruled Cambodia for nearly four decades.

The country’s elections were initially competitive and an opposition tolerated. But in more recent years Hun Sen has turned increasingly autocratic – quashing dissent and jailing critics, forcing many to flee overseas.

He has also cultivated increasingly close ties with China and railed against criticism from Western governments, which he has often accused of helping Cambodia’s political opposition.