This week's gathering of the Communist Party elite in Beidaihe will test President Xi Jinping's authority to hold the party together as senior cadres and interest groups feel the heat from his sweeping anti-corruption campaign, analysts say.
The meeting of party elders and the leadership at the seaside resort for the traditional low-key gathering comes after the president reportedly acknowledged that his two-year-old drive against graft faced challenges.
"The two armies of corruption and anti-corruption are in opposition and are at a stalemate," Xi said, according to state media reports earlier this week.
The reports did not elaborate, but analysts and insiders suggested the widening campaign had damaged interest groups with links to some of the party elite, and Xi had clearly realised that it was make-or-break time in the fight against them.
Renmin University political science professor Zhang Ming said the situation was complicated, and different parties might hit back in Beidaihe.
Zhang said the anti-graft campaign would dominate the informal summit, as leaders were expected to discuss how far the crusade would go, or if any "bigger tigers" would be caught.
"I think the announcement [last week of the formal investigation into former security chief] Zhou Yongkang suggested that Xi did not want to discuss the case at the meeting, but move forward on other possible major corruption cases and issues," he said. "At the centre is what kind of rule of law the leaders want."
Last week, the Politburo said the annual plenary session in October of the party's 205-member decision-making Central Committee would discuss ways to advance the rule of law.
It also announced an investigation into Zhou, who retired from the Politburo Standing Committee in 2012 and is the most senior official to be brought down by graft in modern history.
Xi broke an unwritten rule that incumbent and retired Standing Committee members were immune from corruption investigations, intensifying speculation that some affected political groups were trying to challenge his authority.
Jonathan Holslag, research fellow at the Brussels Institute of Contemporary China Studies, said Xi's biggest challenge was that he was becoming isolated.
"Business leaders are losing patience with his economic policies. The military complains about being stripped of some of its privileges. The party is getting increasingly plagued by distrust and the public is starting to feel that the easy times are over."
One aim of the Beidaihe summit was to reduce behind-the-scenes power struggles and reunite the party under Xi ahead of the annual plenary session, the analysts said.
Steve Tsang, director of the China Policy Institute at the University of Nottingham in Britain, said: "This is meant to deliver a powerful, effective and efficient Leninist party, to enable Xi to introduce the reforms he feels essential to secure the 'China Dream' of promoting a rich and powerful China under the leadership of the party and himself.
"Whether this process of unrelentingly reinforcing the power of the party will gather a momentum of its own, so much so that it just keeps going, is an open question," Tsang added.