The political debut of Hun Manet, 45, marks one of the final steps in a decades-long grooming process that is expected to end with him succeeding his father as prime minister.

Hun Sen in 2021 named his eldest as his choice to succeed him as leader, and his long-ruling Cambodia People's Party soon endorsed him as "future prime minister".

To become prime minister, Hun Manet needs to be a member of the National Assembly, which he will do if he wins a seat on Sunday, as expected, and receive approval from the king.

It is not clear when the transition will happen but some academics suspect that Sunday's election will be Hun Sen's last.

For some, Hun Manet represents a young, fresh face who will further develop Cambodia.

"I came here 15 years ago when there were no skyscrapers," former AmCham President Anthony Galliano said of the capital, Phnom Penh.

He recently hosted Hun Manet as an AmCham guest of honour.

"He is interested in how we could get more investment in the country, how we can improve the brand, the image of the country, to international investors."

But Cambodia's brand is closely tied to Hun Manet's father, who has been a strongman ruler for nearly four decades, and some doubt the son will be any different.

The EIU Democracy Index in February gave Cambodia a score of 0.00 for electoral process and pluralism, a score shared by 28 other countries including some of the world's most repressive.

"He has been exposed to democracy, to human rights and so on. But he has grown up under a very autocratic regime," Kasit Piromya, a former Thai diplomat and foreign minister, who is on the board of ASEAN Parliamentarians for Human Rights, said of Hun Manet.

"The family controls the country," he said. "For him to liberalize himself, then it's the beginning of the end of the family dominance over Cambodian politics. Why should he undermine himself?"

Hun Manet declined to respond to questions for this report, a representative said, while government and party spokespeople did not respond to requests for comment.

It's difficult to gauge what the public thinks of the succession with most independent media shut down and many people afraid to speak out, rights groups say. But Hun Sen's opponents, most of whom are abroad, are scathing.

Self-exiled opposition leader Sam Rainsy denounces what he calls "feudalistic and clan-istic" politics. "For Hun Sen, power means impunity. He knows when he loses power he will lose impunity," he told Reuters in May. "That is why he wants his son to replace him."

WESTERN EDUCATION

Hun Sen has given his son both Cambodian and Western credentials. He said Manet was born from a spirit that emerged from a Banyan tree in a flash of light.

He sent his son to West Point, the first Cambodian to graduate from the U.S. military academy. He then earned a master's degree in economics from New York University and a PhD in economics from the University of Bristol.

In 2003, Hun Manet told his father's biographers that he came to appreciate aspects of American culture - the way people have "the freedom and opportunity to do anything they want", the "tolerance for diversity" and "looking at things from different angles and perspectives".

He also told them a country needed a minimum level of development before democracy could work, otherwise it was easy to manipulate with payments.

In 2015, Manet told ABC that Cambodia must preserve peace, stability and security "at any cost".

Lee Morgenbesser, a professor at Griffith University who wrote a book on authoritarian elections in Southeast Asia, said a Western education does not mean a more moderate ruler.

"Every time the son of a dictator succeeds the dictator, the angle of the story is always that he's a potential reformer, he's a potential moderate, he's a potential progressive, he's Western-educated," Morgenbesser said.

"I've never once seen it turn out to be validated."

'REASSUME ROLE'

As Hun Manet was studied abroad, he also rose up the ranks of the Royal Cambodian Armed Forces (RCAF) - deputy of his father's bodyguards, commander of counter-terrorism, commander of the army, and deputy commander-in-chief.

He also became head of the ruling party's youth wing and joined its standing committee, and raised his international profile.

In 2019 and 2020, Hun Manet met three foreign leaders, the Lowy Institute think tank said. In 2022, after being acknowledged as successor, he met 10.

Hun Sen has indicated that he expects his heir to rule in his own model and if he does not, he might take back power.

"If my son fails to meet expectations ... I would reassume my role as prime minister," he said, according to the Phnom Penh Post.

Asked if his son might govern differently, Hun Sen laughed.

"In what way? Any such divergence means disrupting peace and undoing the achievements of the older generation."

(Reporting by Clare Baldwin; Editing by Kay Johnson and Robert Birsel)

By Clare Baldwin