BEIJING — When President Xi Jinping of China walks into the Great Hall of the People this week to reveal the team of leaders who will help him rule China for the next half decade, all eyes will be on whether the lineup includes one or two younger faces in the running to become his successor.

However, it increasingly appears that may not happen.

Mr. Xi, 64, is scheduled to announce the new lineup of the Politburo Standing Committee, the Communist Party’s top rung, around midday on Wednesday. When he does, several political insiders predict that there will be no members with the youth or background to mark them as heirs apparent.

The Standing Committee lineup will offer the clearest clue yet to a question that has overshadowed the once-in-five-years Communist Party congress now underway in Beijing: how long Mr. Xi may try to stay in control of the world’s newest superpower, either as official leader or as a power behind the throne.

If no successors-in-waiting appear, that would raise new speculation that Mr. Xi may try to keep power in some form after his second five-year term as president ends in 2023. At the very least, it would add a great deal of uncertainty to a succession process that recent Chinese leaders tried to make more predictable and stable.

“The most important outcome of a midterm congress such as this is the designation of a successor,” said Minxin Pei, a professor at Claremont McKenna College in California who studies Chinese politics. “If the old rules apply, we should expect to see a similar outcome. But this time nobody is sure.”

If Mr. Xi does not promote one or more possible heirs into the top tier, he will buck unspoken rules that emerged from the 1990s onward, when Deng Xiaoping tried to ensure a trouble-free train of succession, avoiding a repeat of the chaos during and immediately after the rule of the revolutionary leader Mao Zedong.

Since Deng’s death in 1997, two leadership transitions have followed a pattern that, while not friction-free, gave clarity well in advance about who would take over: Jiang Zemin to Hu Jintao in 2002, and Mr. Hu to Mr. Xi in 2012. But since Mr. Xi came to power at a party congress that year, he has shown a distaste for following his predecessors in lock step.

Even if Mr. Xi does not seek to stay in office beyond 10 years, he may decide that anointing an heir too soon could dilute his own power, turning him into a lame duck. Mr. Xi spent his first five-year term cracking down on corruption in the party, a drive that he also used to impose discipline and establish himself as the strongest Chinese leader in decades.

“Establishing a successor early would create uncertainty for Xi about how long his power remains at a peak,” said Wu Qiang, a current affairs analyst who formerly taught political science at Tsinghua University in Beijing. “Delaying a decision on a successor creates another kind of uncertainty about what Mr. Xi will do in the future. I think he’s not going to make a decision yet.”

Some analysts, such as Mr. Wu, believe Mr. Xi may want to stay in power beyond his second term. Under the current succession practices, he must step down as president, China’s head of state, after two terms, but there is no formal limit on his other main leadership post as head of the Communist Party. Mr. Xi could also try to stay on as chairman of the Central Military Commission, another powerful post atop the nation’s armed forces, or in another newly developed position.

Of course, unexpected turns are still possible. The selection of China’s leaders takes place behind closed doors, making it unclear what the outcome will be until the moment the new lineup is announced. While the procedures are tightly controlled, there have been reversals before.

Even the number of members on the Standing Committee is not clear. The committee has typically had seven members, but even that could change.

Mr. Xi has used the party congress to cement his control over China and the party that rules it. Before the unveiling of the new Standing Committee, the approximately 2,300 delegates at the party congress are expected on Tuesday to approve changes to the Communist Party constitution that will add Mr. Xi’s name to the document, enhancing his halo of power.

The delegates will also approve a new Central Committee, whose 200 or so full members meet once or twice a year to discuss and vote on policy. The Central Committee will in turn meet after the end of the congress to vote in a new Politburo, including its Standing Committee.

The Standing Committee, which meets regularly to discuss policies and make decisions, is where real power resides in China.

Mr. Xi all but certain to stay on the committee, as is his No. 2, Premier Li Keqiang.

But three sources citing people close to party leaders have said a proposed lineup that was circulated before the Central Committee voted did not include the names of any likely heirs. Instead, most of the five candidates for membership were old enough that they may serve just one term.

Such one-term members would be politically beholden to Mr. Xi, giving him the choice to keep them or replace them as he sees fit, perhaps even before the next congress. This could give Mr. Xi the flexibility to appoint a successor toward the end of his second term, and put off diluting his power until he is about to step down.

The three people spoke on the condition of anonymity because of the sensitivity of the secretive discussions. The Times reported last year that Mr. Xi might not put his potential successors into the committee at this party congress.

“Xi seems to be reshaping the rules of the game,” said Joseph Fewsmith, a Boston University professor who studies Chinese elite politics. “This lineup, if it is correct, seems to confirm this.”

The candidates included Li Zhanshu, a policy adviser closely allied with Mr. Xi; Han Zheng, the party secretary of Shanghai; Wang Yang, a vice premier who has handled trade issues; Wang Huning, an ideological adviser who also worked for two previous leaders; and Zhao Leji, the head of the party’s organization department, which screens officials for promotion and transfers.

But Chen Min’er, an official widely seen as a potential heir to Mr. Xi, his boss when they were still both local officials, was not on the list. Nor was Wang Qishan, the hard-charging head of the party’s anticorruption agency, one of Mr. Xi’s closest allies. There had been talk that Mr. Xi had considered keeping him on despite reaching an age, 69, when he is supposed to retire under current unwritten rules.

The names on the list matched a report in the South China Morning Post, an English-language newspaper in Hong Kong, on Sunday. The Times obtained descriptions of the list before that report appeared.