The warnings were not idle. Since the circular was issued, party-run publications and Web sites have vehemently denounced constitutionalism and civil society, notions that were not considered off limits in recent years. Officials have intensified efforts to block access to critical views on the Internet. Two prominent rights advocates have been detained in the past few weeks, in what their supporters have called a blow to the "rights defense movement," which was already beleaguered under Mr. Xi's predecessor, Hu Jintao.
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Mr. Xi's hard line has disappointed Chinese liberals, some of whom once hailed his rise to power as an opportunity to push for political change after a long period of stagnation. Instead, Mr. Xi has signaled a shift to a more conservative, traditional leftist stance with his "rectification" campaign to ensure discipline and conspicuous attempts to defend the legacy of Mao Zedong. That has included a visit to a historic site where Mao undertook one of his own attempts to remake the ruling party in the 1950s.
Mr. Xi's edicts have been disseminated in a series of compulsory study sessions across the country, like one in the southern province of Hunan that was recounted on a local government Web site.
"Promotion of Western constitutional democracy is an attempt to negate the party's leadership," Cheng Xinping, a deputy head of propaganda for Hengyang, a city in Hunan, told a gathering of mining industry officials. Human rights advocates, he continued, want "ultimately to form a force for political confrontation."
The campaign carries some risks for Mr. Xi, who has acknowledged that the slowing economy needs new, more market-driven momentum that can come only from a relaxation of state influence.
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In China's tight but often contentious political circles, proponents of deeper Western-style economic changes are often allied with those pushing for rule of law and a more open political system, while traditionalists favor greater state control of both economic and political life. Mr. Xi's cherry picking of approaches from each of the rival camps, analysts say, could end up miring his own agenda in intraparty squabbling.
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Condemnations of constitutional government have prompted dismayed opposition from liberal intellectuals and even some moderate-minded former officials. The campaign has also exhilarated leftist defenders of party orthodoxy, many of whom pointedly oppose the sort of market reforms that Mr. Xi and Prime Minister Li Keqiang have said are needed.
The consequent rifts are unusually open, and they could widen and bog down Mr. Xi, said Xiao Gongqin, a professor of history at Shanghai Normal University who is also a prominent proponent of gradual, party-guided reform.
"Now the leftists feel very excited and elated, while the liberals feel very discouraged and discontented," said Professor Xiao, who said he was generally sympathetic to Mr. Xi's aims. "The ramifications are very serious, because this seriously hurts the broad middle class and moderate reformers — entrepreneurs and intellectuals," said Professor Xiao. "It's possible that this situation will get out of control, and that won't help the political stability that the central leadership stresses."
The pressures that prompted the party's ideological counteroffensive spilled onto the streets of Guangzhou, a city in southern China, early this year. Staff members at the Southern Weekend newspaper there protested after a propaganda official rewrote an editorial celebrating constitutionalism — the idea that state and party power should be subject to a supreme law that prevents abuses and protects citizens' rights.
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The confrontation at the newspaper and campaign demanding that officials disclose their wealth alarmed leaders and helped galvanize them into issuing Document No. 9, said Professor Xiao, the historian. Indeed, senior central propaganda officials met to discuss the newspaper protest, among other issues, and called it a plot to subvert the party, according to a speech on a party Web site of Lianyungang, a port city in eastern China.
"Western anti-China forces led by the United States have joined in one after the other, and colluded with dissidents within the country to make slanderous attacks on us in the name of so-called press freedom and constitutional democracy," said Zhang Guangdong, a propaganda official in Lianyungang, citing the conclusions from the meeting of central propaganda officials. "They are trying to break through our political system, and this was a classic example," he said of the newspaper protest.