HONG KONG -- When China's new leader, Xi Jinping, visited the country's south to promote himself before the public as an audacious reformer following in the footsteps of Deng Xiaoping, he had another message to deliver to Communist Party officials behind closed doors.
Despite decades of heady economic growth, Mr. Xi told party insiders during a visit to Guangdong Province in December, China must still heed the "deeply profound" lessons of the former Soviet Union, where political rot, ideological heresy and military disloyalty brought down the governing party. In a province famed for its frenetic capitalism, he demanded a return to traditional Leninist discipline.
"Why did the Soviet Union disintegrate? Why did the Soviet Communist Party collapse? An important reason was that their ideals and convictions wavered," Mr. Xi said, according to a summary of his comments that has circulated among officials but has not been published by the state-run news media.
"Finally, all it took was one quiet word from Gorbachev to declare the dissolution of the Soviet Communist Party, and a great party was gone," the summary quoted Mr. Xi as saying. "In the end nobody was a real man, nobody came out to resist."
In Mr. Xi's first three months as China's top leader, he has gyrated between defending the party's absolute hold on power and vowing a fundamental assault on entrenched interests of the party elite that fuel corruption. How to balance those goals presents a quandary to Mr. Xi, whose agenda could easily be undermined by rival leaders determined to protect their own bailiwicks and on guard against anything that weakens the party's authority, insiders and analysts say.
"Everyone is talking about reform, but in fact everyone has a fear of reform," said Ma Yong, a historian at the Chinese Academy of Social Sciences. For party leaders, he added: "The question is: Can society be kept under control while you go forward? That's the test."
Gao Yu, a former journalist and independent commentator, was the first to reveal Mr. Xi's comments, doing so on a blog. Three insiders, who were shown copies by officials or editors at state newspapers, confirmed their authenticity, speaking on the condition of anonymity because of the risk of punishment for discussing party affairs.
The tension between embracing change and defending top-down party power has been an abiding theme in China since Deng set the country on its economic transformation in the late 1970s. But Mr. Xi has come to power at a time when such strains are especially acute, and the pressure of public expectations for greater official accountability is growing, amplified by millions of participants in online forums.
Mr. Xi has promised determined efforts to deal with China's persistent problems, including official corruption and the chasm between rich and poor. He has also sought a sunnier image, doing away with some of the intimidating security that swaddled his predecessor, Hu Jintao, and demanding that official banquets be replaced by plainer fare called "four dishes and a soup."
Yet Mr. Xi's remarks on the lessons of the Soviet Union, as well as warnings in the state news media, betray a fear that China's strains could overwhelm the party, especially if vows of change founder because of political sclerosis and opposition from privileged interest groups like state-owned conglomerates. Already this year, public outcries over censorship at a popular newspaper and choking pollution in Beijing have given the new party leadership a taste of those pressures.
Some progressive voices are urging China's leaders to pay more than lip service to respecting rights and limits on party power promised by the Constitution. Meanwhile, some old-school leftists hail Mr. Xi as a muscular nationalist who will go further than his predecessors in asserting China's territorial claims.
The choices facing China's new leadership include how much to relax the state's continuing grip on the commanding heights of the economy and how far to take promises to fight corruption -- a step that could alienate powerful officials and their families.
"How can the ruling party ensure its standing during a period of flux?" asked Ding Dong, a current affairs commentator in Beijing. "That's truly a real challenge, and it's creating a sense of tension and latent crisis inside the party."
Mr. Xi and his inner circle have about 18 months to consolidate power and begin any big initiatives before preparations for the next Communist Party Congress and leadership reshuffle in 2017 start to consume elite attention, said Christopher Johnson, an analyst on China at the Center for Strategic and International Studies in Washington.
"For now, he's a guy who's trying to be two things at once," said Mr. Johnson, formerly a senior China analyst for the C.I.A. "The question is: How long will they be able to get by with gestures like four dishes and a soup before they have to make the hard choices?"
So far, Mr. Xi has been busy distinguishing himself from his predecessor through an energetic succession of visits and speeches. Mr. Hu, who formally remains state president until next month, when Mr. Xi will take over that post, also came to power accompanied by widespread expectations of change. But he proved to be a rigidly unadventurous leader.
In recent weeks, Mr. Xi has promised to clean up Beijing's noxious smog and make it easier to hail a cab on the city's congested streets. Before that, Mr. Xi also vowed that the party would allow "sharp criticism" of its failings, and said "power must be held in an institutional cage."
Censors have allowed pictures showing Mr. Xi as a relaxed man of the people to spread on the Internet, including one of a jolly encounter with a man in a Santa Claus costume during a trip overseas.
Mr. Xi "doesn't want to be known as Hu Jintao is known, as someone who didn't make much progress," said Ezra Vogel, an emeritus professor of social sciences at Harvard University who recently visited China, a country he has studied for decades.
Yet Mr. Xi has qualified his promises in ways that have already disappointed some proponents of faster market-driven change and political liberalization. In one speech, Mr. Xi said that reform must be piecemeal, citing Deng's dictum that progress is made "crossing the river by groping stones." In another, he said Mao Zedong's era of revolutionary socialism should not be dismissed as a failure.
He has also repeatedly demanded that the military show unflinching loyalty -- a principle that, in his view, the Soviet Communist Party under Mikhail S. Gorbachev fatally failed to uphold.
Mr. Xi, 59, is the son of a revolutionary who worked alongside Mao, until he was purged and jailed. A senior commentator for a major Chinese newspaper said that political patrimony had made Mr. Xi even more sensitive to showing that "while talking about reform, he also wants to tell the party that he won't become a Gorbachev."
Unlike the former Soviet leader, Mr. Xi presides over an economy that, for all its hazards, has grown robustly over three decades, propelling China to greater international influence. But Chinese officials have warned that rising stature is also generating external rivalries and domestic demands that would magnify the damage from political missteps and schisms.
"We're a major power, and we absolutely cannot allow any subversive errors when it comes to the fundamental issues," Mr. Xi told party officials in Guangdong. "If that happens, there's no going back."
Edward Wong contributed reporting from Beijing.
This article originally appeared in The New York Times.