BEIJING, Sept 4 (Reuters) - President Xi Jinping of China is expected to place trusted allies in the Communist Party's key decision-making Politburo during a leadership reshuffle at the 19th party Congress this autumn, according to multiple Chinese sources and foreign diplomats.
A key measure of Xi's power will be how many of his allies are installed on the 25-member committee.
At least 10 Politburo members are slated to retire due to an unwritten rule that politicians step down if they are 68 or older when they take on a new five-year term.
And the youngest Politburo member, Sun Zhengcai, 53, is out of the running. He served as Chongqing party boss before being put under investigation in July for disciplinary violations, Communist Party jargon for corruption.
The fate of the top corruption watchdog, Wang Qishan, 69, is also the subject of widespread conjecture. It is unclear if he will retain his seat in the elite seven-member Politburo Standing Committee, despite his age, and therefore his spot on the wider Politburo.
The State Council Information Office, which doubles as the spokesman's office for the cabinet and party, declined to comment on Politburo candidates when reached by telephone and fax. Possible newcomers to the Politburo among Xi's allies (surnames in alphabetical order):
* Cai Qi, 61, has enjoyed a meteoric rise under Xi and is considered a shoo-in after he was named party boss of Beijing in May, despite not being a full or alternate member of the wider Central Committee. He has been a Politburo member since 1987. Cai overlapped with Xi during the future president's 17-year stint in the southeastern province of Fujian, and in the eastern coastal province of Zhejiang, where Xi was party boss from 2002 to 2007. Cai is a native of Fujian.
* Chen Miner, 56, was seen to have performed strongly as the leader of Guizhou province before being named party boss of the southwestern metropolis of Chongqing on July 15, replacing Sun. Chen, a native of Zhejiang, is also virtually assured of a seat in the Politburo given his position in Chongqing, the sources said. Chen is a dark horse candidate to catapult straight onto the Standing Committee.
* Chen Quanguo, 61, was promoted to party chief of the restive far-western region of Xinjiang, bringing along with him the tough ethnic management policies he implemented at his previous post in Tibet. Chen has never worked closely with Xi.
* Chen Xi, 64 this month, a native of Fujian, is tipped to be promoted to minister of the party's organisation department, overseeing the promotion and deployment of party officials. He is currently vice-minister at the department. Chen shared a dormitory with Xi when the two attended the prestigious Tsinghua University in the late 1970s.
* Ding Xuexiang, 55 this month, is likely to become director of the General Office of the Central Committee. He is currently No 2 in the General Office, which oversees day-to-day operations of the Politburo. Ding worked for Xi when the latter was party boss in Shanghai.
* He Lifeng, 62, chairman of the cabinet's National Development and Reform Commission, is a strong candidate to become one of five state councillors, a rank above cabinet minister but below vice premier. If he is named one of four vice premiers next March, he would be a favourite for the Politburo. He worked in Fujian from 1984 to 2009, overlapping with Xi, who was governor from 2000 to 2002.
* Huang Kunming, 60, a native of Fujian, is the front-runner to become the party's propaganda minister. He is currently No 1 vice-minister. He followed Xi from Fujian to Zhejiang.
* Li Hongzhong, 61, is party secretary of the northern port city of Tianjin. He never worked under Xi previously, but has been an ardent supporter of Xi's policies.
* Li Qiang, 58, a native of Zhejiang, is currently party boss of the eastern coastal province of Jiangsu. Li was Xi's right-hand man when Xi was party boss of Zhejiang.
* Li Xi, 60, currently party chief of the northeastern province of Liaoning, is seen to be in line for promotion to head a bigger province. He once worked in Xi's home province, Shaanxi, in China's northwest.
* Liu He, 65, is Xi's key economic advisor and a strong candidate to become a state councillor or vice premier. When then-U.S. National Security Adviser Tom Donilon visited Beijing in 2013, Xi introduced Liu as "very important to me", according to the Wall Street Journal. Liu holds a master's degree in public administration from Harvard University's Kennedy School of Government.
* Ma Xingrui, 57, was once the chief engineer of China's lunar programme. Now the governor of Guangdong province, he is one of two candidates for party secretary, the top post, in the booming southern region. If successful, he would be assured of a Politburo seat.
* Wang Xiaohong, 60, is a candidate to lead either the police or the national security apparatus. He is currently a vice minister of public security and a vice mayor of Beijing. Wang cut his teeth in his home province Fujian, overlapping with Xi.
* Xia Baolong, 64, once touted to take over as security tsar, stepped down as party boss of Zhejiang province in April. In a surprise move, he was sidelined to the No 2 position in parliaments environmental protection and resources conservation committee, which may hurt his chances to join the Politburo. Xia, who ordered the tearing down of hundreds of church crosses in Wenzhou city in 2015, was Xi's deputy in Zhejiang.
* Ying Yong, 59, a native of Zhejiang, is currently mayor of Shanghai and a candidate to become party boss of the countrys financial capital. He worked under Xi in Zhejiang as deputy police chief, the No 2 corruption watchdog and an appeals court acting chief judge.
* You Quan, 63, has been the Communist Party secretary of coastal Fujian province since December 2012. A native of Hebei province with a background in economics, he is a former chairman of the State Electricity Regulatory Commission. (Reporting by Benjamin Kang Lim and Philip Wen; Editing by Tony Munroe)