China's ruling communists were handed a list of candidates for their new Central Committee on Tuesday ahead of a tightly circumscribed vote to select a new leadership for the world's most populous nation.

The margin for Wednesday's election of committee members is slightly more than 8 per cent, meaning there are 108 candidates for every 100 seats, the party said, though it did not give the exact number. The measure is intended to introduce a degree of competition amid calls for greater intra-party democracy within China's authoritarian, one-party system.

The congress' presidium headed by leader-in-waiting Xi Jinping handed down the list of carefully vetted candidates Tuesday to the 18th national congress delegates, who number just under 2,300 delegates. About 200 will be elected, along with their alternates.

The Central Committee will then elect the 25-member Politburo and its Standing Committee, the apex of power in China, which currently has nine members, but may shrink to seven. The congress also will appoint a party disciplinary body to investigate corruption and other abuses, and a Central Military Commission to oversee the 2.3 million-member People's Liberation Army.

While Xi and future Premier Li Keqiang were designated as successors five years ago, the jockeying for other positions is believed to be intense. Speculation also has swirled over whether party leader Hu Jintao will relinquish his title of military commission chairman and how many allies he will manage to elevate to the Standing Committee.

Hu called for broader reforms in his speech at the congress' opening last week, but offered nothing specific. He is to give up his party title at the end of the congress on Wednesday and the presidency next spring, after a decade in power.