JIAXING, China -- Chinese President Xi Jinping turned 68 this week, the customary retirement age for the Communist Party's top leaders, fueling speculation as to whether he will buck tradition to remain leader at the Communist Party's National Congress in 2022.

Members of the powerful Politburo Standing Committee generally retire if they are 68 or older at the twice-a-decade party congress. Xi, who celebrated his birthday on Tuesday, Li Zhanshu, National People's Congress Standing Committee chair, and Vice Premier Han Zheng would all fall above this threshold at the next party congress.

The unwritten rule is generally considered a way to prevent any one figure from remaining in power too long and undermining the principle of collective leadership. But some in the party say it was really only introduced by former President Jiang Zheming, in office from 1993 to 2003, to push out his older rivals.

Xi has signaled that he plans on remaining in power for quite some time.

In 2018, China amended its constitution to scrap a two-term, 10-year limit on the presidency. Some also believe that Xi wants to become party chairman, a post abolished after Mao Zedong's death to prevent another leader for amassing so much power.

Still, it is unclear whether Xi's ambitions would bear fruit. At the last party congress in 2017, Wang Qishan stepped down from the Politburo Standing Committee in line with the age threshold to become vice premier instead. The party is also believed to have discussed and punted the idea of reviving the chairman post then as well.