Such changes would curb the state’s role, lessen corruption and encourage competition. But making them would involve a titanic power struggle. Executives of Chinese conglomerates, army generals, Politburo members, local officials and the “princeling” children of Communist Party elders have little incentive to refashion a system that fills their coffers.

Another significant aspect of the China model is the growing security apparatus. Its heavy-handed tactics in pursuit of social stability have been called into question by, among other things, more than 30 self-immolations by disaffected Tibetans and a diplomatic crisis between China and the United States precipitated by the plight of a persecuted dissident, Chen Guangcheng. A well-documented uprising last winter against corrupt officials in the southern village of Wukan ignited a debate about how protests should be addressed: by the sword of the security forces, or through mediation by senior officials.

But it is the scandal over Bo Xilai, until recently a member of the party’s elite Politburo, that has most humbled those who previously praised the well-oiled nature of China’s political system and its appearance of unity.

Before the charismatic Mr. Bo lost his party chief post in Chongqing, other leaders were already starting to view him as an increasingly intolerable maverick. After arriving in Chongqing in late 2007, Mr. Bo began what was billed as a crackdown on crime, along with a revival of Mao-era singalongs and welfare policies, aimed at generating populist backing and winning political support from the “new left,” or hard-core socialists, for his bid to join the top-level Politburo Standing Committee, which is scheduled to turn over this year.

Mr. Bo’s bid veered sharply from the traditional route of ascension, which since the era of Deng Xiaoping has been one of back-room patronage and shadowy negotiations among party elders. The problem now in China is that the powers of those elders have diminished with each generation — the current president and party chief, Hu Jintao, is weaker than his predecessor, Jiang Zemin, who was much weaker than Mr. Deng.