Two years into his presidency China's Xi Jinping has overturned his image as a consensus-builder, with some analysts questioning whether the Communist Party would have chosen him as leader if the full scope of his ambitions and his signature anti-corruption drive had been known.

Xi, who is also general secretary of the Communist Party, was widely viewed as a compromise candidate between rival factions when he took office two years ago Saturday, winning approval from both influential former president Jiang Zemin and Xi's predecessor, Hu Jintao.

At the helm of a party whose prime goal is ensuring its own continued rule, Xi was expected to continue the leadership's risk-averse approach -- but instead, experts say he has confounded expectations by presiding over a far-reaching anti-graft campaign and a harsh crackdown on activists, sending shockwaves through the ranks of the party elite and civil society alike.

"If anybody had had any inkling of what was going to happen, he would not have been picked," said Minxin Pei, a professor of government at Claremont McKenna College who has written two books on contemporary Chinese politics.

After the death in 1976 of Communist China's founding father Mao Zedong -- who was at the centre of a huge personality cult -- the party became deeply conservative politically, Pei said, with its innermost circle selecting top leaders who would respect a new set of norms.

There was to be a consensus-based decision-making process, a respect for the physical safety of other party members and -- crucially -- no strong leaders.

"Both Jiang and Hu were in that mould," Pei said, noting that other than Xi, the six remaining members of the party's elite Politburo Standing Committee "are people who will not rock the boat".

But Pei added: "In the case of Xi, they've got the mother of all boat-rockers. The people who picked him must be regretting bitterly that they picked somebody who turned out to be completely different."

- 'A broad revivalist effort' -

Xi's anti-corruption sweep has been the signature of his first two years in office.

While critics say the absence of systemic reforms means it can be used for factional political purposes, the campaign has extended through government, military and state-owned enterprises' ranks, felling officials as powerful as former internal security chief Zhou Yongkang and former Central Military Commission vice-chairman Xu Caihou.

In another departure from his predecessors, Xi has positioned himself as the head of a half-dozen core leadership groups within the party.

He also recently unveiled a new theory, the "Four Comprehensives", that underscores the breadth of his agenda. Its goals: "Comprehensively build a moderately prosperous society, comprehensively deepen reform, comprehensively govern the nation according to law, and comprehensively strictly govern the Party".

At the same time, China under Xi has clamped down on dissent, with hundreds of activists, lawyers, journalists and others rounded up in what rights groups have called the most alarming such crackdown in decades.

That campaign took its latest turn last week, when five women's rights campaigners were detained in Beijing for planning protests against sexual harassment on International Women's Day. Amnesty International decried the detentions as "chilling" and the European Union has demanded their release.

Barry Naughton, a professor at the University of California, San Diego, said that Xi has been changing China in fundamental and diverse ways, and the extent of his ambitions signals "a broad revivalist effort to make himself a more powerful leader than others have been and to revive the whole Communist Party system".

Xi has proved "much more dynamic and formidable" than many had expected, added Naughton, an expert on China's economy. "We really need to take him very seriously."

Scholars are divided, however, on whether the successes of Xi's campaign outweigh the actual and potential costs.

- 'More scalps' -

Some say the anti-graft drive is clogging up the wheels of government by stripping away the oil that kept them turning.

"There is a kind of wait-and-see attitude -- a lack of lubricants on the one hand, and a sense of insecurity," said Joseph Cheng, a politics professor at the City University of Hong Kong. "And so, there is a tendency not to start important projects, not to start important initiatives, and this has affected economic growth and party morale."

In a commentary Thursday, China's official Xinhua news agency insisted: "Instead of derailing China's economic and political train, the storm is revitalising a country long plagued by corruption."

Xi and other top Chinese leaders are determined to avoid the fate of the Soviet Union, where Communist leader Mikhail Gorbachev "was seen to destroy the party in order to introduce reforms", Cheng noted.

"So the emphasis on the power of Xi Jinping now is that they must maintain the integrity of the leadership of the party, strengthen the ideological line and discourage Western thinking."

Steve Tsang, a China politics expert at the University of Nottingham, said the lack of a clear end in sight for Xi's anti-graft drive "is causing much concern and discomfort among some of his colleagues" -- but that if the momentum stops, Xi's dissenters within the establishment could be emboldened to push back.

"It may or may not require ever bigger scalps, but more scalps will certainly be needed," Tsang said. "He has now put himself in a position by which he has to keep going to avoid falling off."