The 19th National Congress of the Communist Party of China (CPC), which opens on October 18, could have been another crucial step on Sun Zhengcai’s path to holding a top leadership role in China’s ruling party. But under the ironclad rule of Xi Jinping, such hopes have apparently been dashed.

When Sun was elevated to the Politburo at the CPC’s 18th National Congress five years ago, the rising star was highly tipped to become a future leader of the 90-million-member CPC and the 1.3-billion-population People’s Republic of China.

The then youngest member of the Politburo – composed of the Communist-run country’s 25 most powerful politicians – was even touted as a potential successor to Xi Jinping, the current leader.

But on September 29, just three weeks ahead of the five-yearly gathering, where the one-party state’s leadership succession is decided, the ultra-powerful Politburo decided to expel Sun, 54, from the party and strip him of all titles for “serious discipline violations”.

With such a decision, not only did his highly promising political career end, the former party chief of Chongqing is now also facing criminal prosecution and possibly a lengthy prison sentence.

His sudden downfall has stunned many, including the Global Times. In its editorial on September 30, the state-run newspaper said: “As a rising young official, Sun left a deep impression upon people as all his promotions proved plain sailing. As a result, his fall came as a shock.”

His tumble from grace is startling, not only because he was a rising star and only the fourth sitting Politburo member to be brought down in 30 years, but also because of the abrupt and brutal manner of his demise.

As recently as about three months ago, he was still expected to be promoted to the seven-seat Politburo Standing Committee (PSC), the PRC’s highest decision-making body – putting him on course for a top leadership post after 2022. But at a hurriedly arranged meeting of senior Chongqing officials on July 15, he was removed as the 30-million-population city’s party chief and put under investigation. Sun then totally disappeared from view.

Just two and a half months later, based on a report on his investigation, his comrades in the Politburo formally and pitilessly decided his fate.

The investigation conducted by China’s top anti-graft body, the Central Commission for Discipline Inspection, found that Sun was guilty of various and serious offenses.

As reported by Xinhua, the country’s strictly censored official news agency, these included nepotism and abuse of power. The former party secretary of the southwestern Chinese city was accused of “seeking benefits in selection of officials”, “[taking] advantage of his power” and “[influencing] to seek benefits for others”.

But while it is unclear whether Sun truly committed the acts of which he was accused, it is apparent that President Xi Jinping is practicing them.

It is widely maintained that Xi, who has amassed sweeping powers since he came into office in 2012, has sought to promote his loyalists.

Chen Min’er, who was appointed Chongqing’s party chief in July after Sun’s shock removal, is universally seen as Xi’s protégé and has been fast-tracked for promotion. Chen, 57, worked under Xi when the latter was party secretary of Zhejiang province. As the leader of China’s fourth-largest city, Chen, a member of the 205-seat Central Committee, is sure to be elevated to the Politburo, and likely the PSC, at the upcoming conclave.

According to figures compiled by The Economist, from January 2016 to May this year, Xi replaced 20 of the country’s 31 provincial secretaries and shuffled 27 of the provincial governorships. In contrast, between January 2006 and May 2007 – the comparable midway period in the rule of Hu Jintao – only 12 party secretaries and 11 governors were replaced. This means Xi replaced twice as many provincial party chiefs and governors (the top two positions at a regional level) as his predecessor in the equivalent period.

During their respective reins, Jiang Zemin and especially Hu Jintao, Xi Jinping’s two immediate predecessors, positioned themselves as primus inter pares. But now, Xi is not simply first among equals, but simply first or above all

Tellingly, nine of these newly appointed officials held office in Zhejiang when Xi was the eastern province’s party chief (2002-2007).

One of these is Cai Qi, who was nominated Beijing’s party secretary, a position that will probably ensure his seat in the Politburo at the 19th  Congress. Chen Min’er was also among these. The former director of Zhejiang’s propaganda department was appointed Guizhou province’s party chief before being moved to Chongqing in July.

The Global Times commented that China’s anti-corruption drive since 2012 “has made it clear that every individual is equal before Party discipline and laws and that no one enjoys any privileges”.

But again, this apparently doesn’t apply to President Xi.

During their respective reins, Jiang Zemin and especially Hu Jintao, Xi’s two immediate predecessors, positioned themselves as primus inter pares. But now, Xi is not simply first among equals, but simply first or above all.

In addition to assuming his traditional roles – that is, head of the party, the state and the military – he has acquired a series of other important titles and roles, making him “China’s chairman of everything”.

Whether it was his party’s wish or his own desire, he has already been officially elevated to status as the country’s “core” leader. The impending Congress is expected to secure furthe his unchallenged status in the party hierarchy, putting him in the same revered ranks as Mao Zedong and Deng Xiaoping.

Without doubt, Xi enjoys many privileges that Jiang and Hu did not. Even Mao and Deng might have envied his extensive powers, because some of the most prominent groups or commissions currently headed by Xi only came into existence under his rule or by his own creation.

Moreover, many signs – such as the absence of potential successors like Sun on the Standing Committee – indicate that Xi, 64, may even break the CPC precedent and remain China’s supreme leader beyond his second term that ends in 2022.

All of this, coupled with the fact that Sun Zhengcai’s shock removal came just weeks before the party’s all-important meeting, makes people question whether Sun and many other “tigers” (senior officials) and “flies” (lower-ranking cadres) have fallen under Xi’s fierce anti-corruption campaign purely because they were corrupt or because of something else.

Bo Xilai, who was convicted of corruption and sentenced to life imprisonment in 2013, was once viewed as Xi’s greatest rival. It is also speculated that Sun Zhengcai was purged because the rising star posed a challenge and even a threat to Xi’s rule.

In any case, that a high-level official and indeed an heir apparent such as Sun Zhengcai was purged in such a brusque manner, just weeks before the party’s National Congress, hints that China’s politics under Xi’s regime is unpredictable. Sun’s sudden elimination and many other developments in China over the past five years also indicate that Xi’s rule is more ruthless and autocratic than that of Jiang and Hu.