Already China's most powerful leader in decades, President Xi Jinping will probably seek to extend his term to more than 10 years, analysts say, the first Communist Party chief to do so since Deng Xiaoping.

The ruling party's leaders have reportedly gathered at their secretive annual Beidaihe retreat on the northern Chinese coast, where discussions are expected to focus on the composition of its next all-powerful Politburo Standing Committee (PSC).

The 19th Party Congress, slated for next year, will decide a new PSC line-up, traditionally seen as indicating Xi's most likely successor after he steps down, due in 2022.

But Xi has thus far delayed anointing an heir. And while Chinese Communist leaders have often maintained influence after their official retirement, scholars and analysts increasingly believe Xi will try to stay in office beyond his standard term.

"A lot of analysts now see it as a given" that Xi will seek to stay party general secretary, the country's most powerful post, said Christopher K. Johnson, a former CIA analyst and now China specialist at the Washington-based Center for Strategic and International Studies.

Willy Lam, expert on politics at the Chinese University of Hong Kong, said there was a 60 to 70 percent chance that Xi would refuse to give up the role.

Doing so would violate the unofficial rule set by Deng Xiaoping, who led China from 1978-1989, that general secretaries stay in office no longer than 10 years. That principle has helped smooth transfers of power within the party since the 1990s.

As well as ensuring regular renewal at the top, and opportunities for different Communist Party factions to dominate at different times, the concept also seeks to prevent the emergence of a despot.

- 'No heir apparent' -

China's constitution sets term limits for presidents and ministers, but there is no such rule for the party secretary.

Analysts say if Xi's close ally Wang Qishan, a PSC cadre who is due to retire, is allowed a second term it could establish a precedent for the party chief.

Xi has made his enduring ambition clear by installing himself as chairman of most of the powerful new groups within the party, said Victor Shih, professor at the University of California, San Diego.

Doing so "increases the threshold for anyone to replace him," he told AFP. "Moreover, there is no heir apparent now."

Xi has already smashed several unwritten party rules since ascending to general secretary in 2012, Johnson noted.

His anti-corruption drive felled the once hugely powerful security chief Zhou Yongkang, breaking the tacit understanding that former top leaders were immune to such campaigns -- and giving him an incentive to stay in power.

More time as president could allow Xi to follow through on long-promised reforms and bolster his more assertive foreign policy in the South China Sea, experts say.

Xi's allies could argue a longer term would let him pursue his ambitious targets of national rejuvenation and doubling 2010 per capita income by 2020, in time for the 100th anniversary of the party's founding.

- Modelled on Putin -

Xi has already reduced the strongest potential source of challenges by establishing his grip over the military and police, Lam said.

The Party last week imposed tighter controls on the Communist Youth League, a key power base of Xi's rivals which has produced some of the country's top leaders, including former president Hu Jintao as well as premier Li Keqiang.

Analysts say Xi sees an enviable model in Russia's Vladimir Putin, who has successfully kept power for well over a decade by bouncing between the offices of president and prime minister.

"Like his good friend Putin, (Xi) wants to have more than two terms in power," said Lam.

But while Xi has openly admitted he admires Putin, following his example presents challenges, said Bo Zhiyue, professor of Chinese politics at the Victoria University of Wellington in New Zealand.

"Putin can switch his positions without losing his power, but in Chinese politics that's not possible," he told AFP, adding that staying on as general secretary but not retaining the presidency would make Xi a "less powerful leader".

And the collapse of Russia's own Communist predecessor, the Soviet Union -- something Xi sees as anathema -- itself holds warnings for the Chinese leader, said the University of California's Shih.

In Moscow, a series of increasingly geriatric leaders held power until their deaths, he pointed out, which was "partly responsible for the sclerosis in late Soviet politics".

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