“Some have turned to believe in violent revolution,” said Hu Jia, a prominent dissident who served more than three years in prison for his activism and still faces routine surveillance. “It makes people feel the door to a peaceful transition has closed.”

Mr. Liu’s allies remain incensed by the Chinese government’s handling of his case. Officials disclosed that Mr. Liu, 61, had advanced liver cancer only when it was too late to treat it, prompting accusations that his medical care was inadequate. The authorities have also prevented his wife, Liu Xia, an artist and activist, from speaking or traveling freely.

The scrutiny facing government critics is likely to grow even more suffocating in the months ahead.

The Communist Party will hold a leadership reshuffle this fall, at which Mr. Xi is expected to win another five-year term and appoint allies to key positions. In the run-up to the meeting, the party is tightening its grip on online communications and escalating pressure on critics.

Human rights advocates say that the party appears increasingly hostile toward dissent and intent on quashing even small-scale movements. Over the past two years, dozens of human rights lawyers have been jailed and accused of conspiring with foreign forces to carry out subversive plots. Mr. Xi’s government, wary of grass-roots activism, has also increased oversight of domestic and foreign nonprofit organizations.

Yaxue Cao, an activist who grew up in China but is now based in the United States, said Mr. Liu’s death was “the climax of a long and continuous stretch of ruthless elimination.” She recited a long list of critics who had been sidelined since Mr. Xi rose to power in 2012, which she said had led to a culture of fear and intimidation.

“The party has been working systematically to block the path forward,” she said. “A few hundred or a few thousand activists are nothing for the party.”