BEIJING, Oct. 18 (Xinhua) -- More than 2,200 party delegates began to scrutinize a list of nominees Thursday before making their choice on who would enter the central committee of China's ruling Communist Party.

The list, endorsed by the 237-member presidium of the 17th National Congress of the CPC Wednesday, was prepared by a special working group under the Political Bureau of the 16th CPC Central Committee, spokesman of the congress Li Dongsheng has said.

Those on the proposed list will have a chance to become candidates of members and alternate members of the central committee, and members of the central discipline commission.

The five-yearly congress will first hold a primary election before a final ballot, a practice since the 13th party congress in1987.

The personnel reshuffle is one of the most important agenda of party congress. The constitution of the CPC rules that all election should be carried out through secret ballot.

The CPC adopted a primary election system at its 8th national party congress in 1956. Then at the 13th national congress in 1987,it began to follow a differential voting system at the primary election, hailed as a major progress in the CPC intra-party democracy.

At that congress, five percent of nominees lost in the primary election for candidates of members of central committee, and 12 percent of nominees lost in the election for candidates of alternate members.

The margin of elimination in the vote of the 14th and 15th national congresses were not released. The 16th party congress, however, recorded a margin of elimination at a little more than five percent.

At the 16th party congress in 2002, members of the central committee were elected with a 5.1 percent margin, and alternate members of the central committee, 5.7 percent. Seven people lost in the primary vote for members of the Central Discipline Commission, marking a 5.8 percent margin.

There have been quite some speculations that the margin this time may be higher as Hu Jintao said in his report to the congress that the party should "expand intra-party democracy."

"We will reform the intra-party electoral system and improve the system for nominating candidates and electoral methods," he said in the report.

In choosing delegates prior to the congress, all 38 constituencies adopted a 15 percent margin in the elections, five percentage points higher than that in 2002.