Now, Mr. Xi faces an accelerating health crisis that is also a political one: a profound test of the authoritarian system he has built around himself over the past seven years. As the Chinese government struggles to contain the virus amid rising public discontent with its performance, the changes that Mr. Xi has ushered in could make it difficult for him to escape blame.

“It’s a big shock to the legitimacy of the ruling party. I think it could be only second to the June 4 incident of 1989. It’s that big,” said Rong Jian, a writer about politics in Beijing, referring to the armed crackdown on Tiananmen Square protesters that year…

That retreat from the spotlight, some analysts said, signaled an effort by Mr. Xi to insulate himself from a campaign that may falter and draw public ire. Yet Mr. Xi has consolidated power, sidelining or eliminating rivals, so there are few people left to blame when something goes wrong.

“Politically, I think he is discovering that having total dictatorial power has a downside, which is that when things go wrong or have a high risk of going wrong, then you also have to bear all the responsibility,” said Victor Shih, an associate professor at the University of California San Diego who studies Chinese politics.