TWO DAYS after Americans vote, a very different political process will get underway in China. The result is known, and it has been for five years: Xi Jinping, 59, a career apparatchik, will be installed as general secretary of the Communist Party, the country’s most powerful position, while Li Keqiang will be “elected” as his deputy. How or why the two men were chosen is unknown outside the highest echelons of the Chinese leadership; their political inclinations and plans for China are also a matter of guesswork. It’s not clear who will serve with them in the party’s Standing Committee, which makes decisions by consensus, or even how many members the committee will have.

What is clear is that the political system the leaders will inherit is under growing pressure. Many within the Communist Party’s elite — not to mention the country’s rapidly growing middle class — consider the status quo unsustainable. Under the previous leaders, Hu Jintao and Wen Jiabao, the economy quadrupled in size, and China emerged as a global power, but the Stalinist structure installed by Mao Zedong in the 1950s remained essentially unchanged. Even Mr. Wen appears to think that is untenable. “Without successful political structural reform,” he said this year, “new problems that have cropped up in China’s society will not be fundamentally resolved.”

The “new problems” are legion: Popular protests, mostly in rural areas, occur at the rate of more than one a day; in cities, spontaneous mobilizations have stopped the expansion of a chemical plant and a copper refinery. Despite the world’s largest censorship apparatus, authorities have been unable to control burgeoning free expression on the Internet, including China’s version of Twitter, Sina Weibo, which has 300 million accounts.

China’s reformers don’t expect the country to become a democracy overnight. But the new leaders finally could begin to modernize the system. They could allow independent social groups and nongovernmental organizations at the local level and, eventually, contested elections for local assemblies. Corruption, which threatens to choke the economy, could be better controlled if the news media and social media were freer. Resources could be shifted from wasteful investments in infrastructure and state companies to consumers and services.

Mr. Xi has given no indication whether he favors such reforms. Some Western reports suggest he may be liberal-minded, while others speculate he is close to the Chinese military and could choose nationalism and conflicts with outsiders, including the United States, over domestic change. Either way, the next decade in China will be more turbulent and unpredictable than the last. Whoever wins Tuesday’s presidential election will have little control over China’s course; but he will have an opportunity to nudge Mr. Xi in the direction of democratic change.