The main player is the region’s powerful party secretary, Bo Xilai, the closest China has to a Western-style politician. A tall, suave 63-year-old, Mr. Bo has intrigued foreign and domestic political watchers for two decades — as mayor of a port city, provincial governor, commerce minister and now head of Chongqing, a city-state the size of Austria with 30 million people. Unlike Mr. Xi, seen as humble and deft, Mr. Bo is a tenacious fighter and showman.

He is also a contender for the Standing Committee of the party’s Politburo, which would put him among the nine people — with Mr. Xi at the head — who have final say on everything from currency exchange rates to Tibet.

But Mr. Bo’s chances have suffered a serious blow because of an unfolding corruption scandal involving Wang Lijun, the man he recruited as Chongqing’s top law enforcement officer. While some observers say Mr. Bo’s ascension cannot be ruled out, most seem to think his upward trajectory has stalled.

Until recently, Mr. Bo’s tenure in Chongqing had seemed brilliant. For most of his political ascent, Mr. Bo relied on his father, Bo Yibo, a revolutionary war leader who died only in 2007. As the offspring of a top-ranking official, or “princeling,” he is part of a network of people who can bypass normal channels, both for personal and political gain.

Mr. Bo used these connections to carry out a series of populist changes in Chongqing. Once the wartime capital of China, it was expanded in the 1990s into a small, mostly rural province with a metropolis at its center.