The Chinese government on Monday voiced strong support for Hong Kong’s embattled chief executive, Carrie Lam, a day after yet another vast street protest against her government rattled the leadership in Beijing and the local political establishment.

The Foreign Ministry issued a forceful endorsement of Mrs. Lam on Monday. Beijing’s representatives in Hong Kong called in dozens of local politicians and business leaders to urge them to support her. And the Chinese state media began praising Mrs. Lam even as government censors assiduously tried to block word of the Hong Kong protests from reaching the public in mainland China.

But after three huge demonstrations over eight days, and her retreat on a proposal that would have allowed Hong Kong residents to be prosecuted in China’s opaque judicial system, it was unclear how long she would continue to govern.

The latest protest, on Sunday, was the largest yet, with a crowd that organizers estimated at almost two million in a city of seven million people. While Mrs. Lam had indefinitely suspended her push for the Beijing-backed extradition bill the day before, protesters still filled the streets, calling for her to withdraw the legislation instead of suspending it, and demanding that she resign.

While Mrs. Lam, a lifelong veteran of Hong Kong’s fractious politics who was appointed chief executive two years ago, has refused to bow to the protesters’ jeering calls for her to quit, democracy advocates in Hong Kong vowed to press on.

“Carrie Lam must step down,” said Joshua Wong, a student leader who, coincidentally, was released from prison on Monday after serving a two-month sentence for refusing to leave a protest site in 2014 during a democracy push known as the Umbrella Movement.

“More and more Hong Kong people — not only one million, two million people — will come to join our fight until we get back our basic human rights and freedom,” he said.

In addition to calling for Mrs. Lam to step down and fully withdraw the bill, the protesters — emboldened and angered after her partial concession on Saturday — have called for an impartial investigation into the police use of force against demonstrators and for a rescinding of the official description of clashes with the police on Wednesday as an illegal riot.

On Monday night, the territory’s top police official tried to address the last demand, saying that only five people had been charged with rioting and that the police did not consider those who participated peacefully in the protest to be rioters. But he brushed aside accusations that officers had used excessive force.

Any resignation by Mrs. Lam would prompt strong demands by democracy activists for her successor to be chosen in free and open elections. But the Communist Party leadership in Beijing, loath to allow any steps that might jeopardize one-party control on the mainland, is unlikely to let them be held.

The political sensitivities over the events in Hong Kong were evident as the Chinese authorities worked around the clock to keep most of the mainland in the dark about the demonstrations.

On Monday, online censors continued to delete reports and images from the protests. While the terms “Hong Kong” and “against extradition to China” were among the most popular queries on the microblogging platform Sina Weibo, according to, which tracks censorship on the site, searches turned up only limited results, some describing protesters as thugs.

Searches for the term “Hong Kong protests” returned mostly state-approved news, often portraying the demonstrations as instigated by foreign forces, while queries of “Fight on, Hong Kong” were blocked altogether by reason of “relevant laws and regulations.” There was no mention of Hong Kong on the Monday evening news on CCTV, the main state broadcaster.

Some on the mainland were able to circumvent censors by posting inverted or distorted images of the protests. Others appeared to make more oblique references to the protests, posting Cantonese songs like Lo Ta-Yu’s “Queen’s Road East” and “Boundless Oceans, Vast Skies” by the Hong Kong rock band Beyond.

Hu Jia, a prominent dissident in Beijing, said he had learned about what was happening in Hong Kong only on Thursday, four days after the first protest, which organizers said drew more than one million people.

Like many other activists, Mr. Hu said he had been under increased scrutiny by the authorities recently because of the 30th anniversary of the June 4, 1989, crackdown in Tiananmen Square. With China now blocking many virtual private networks, or VPNs, which some Chinese surreptitiously use to connect to the outside world, he struggled for days to find information.

When he was finally able to connect and see the events in Hong Kong, he said, he was “moved to tears.”

“After the Umbrella Movement was suppressed in 2014, I thought there would be no way that Hong Kong could have this kind of democratic expression again,” Mr. Hu said in a telephone interview.

“But what happened in the last week was like magic,” he added. “I suddenly felt as if Hong Kong’s flower of freedom had opened again, and it was very bright.”

In Beijing, there were signs of political uncertainty. The Foreign Ministry’s English-language translation of the news conference where the government endorsed Mrs. Lam omitted any reference to her. And 10 academics in Beijing who focus on Hong Kong, some of whom were eager to speak about the issue last week, turned down requests for comment on Monday. Several said it was an inconvenient time.

That caution set in as the Chinese government made clear that, at least temporarily, it would come to Mrs. Lam’s political rescue.

The Central Liaison Office, which represents the Chinese government and the Communist Party in Hong Kong, gathered dozens of business leaders and pro-Beijing local politicians on Sunday at its offices to ask that they maintain their support for Mrs. Lam.

Those in attendance then vied on Sunday and Monday to show who could show the most loyalty to Mrs. Lam. Chan Wing-kee, a pro-Beijing lawmaker, used an enthusiastic local Cantonese term to say that he “very much supported” Mrs. Lam.

While Beijing may be reluctant to be seen as conceding to public pressure and sacrificing Mrs. Lam immediately, there was intense speculation in Hong Kong about whether she would be allowed to serve out the remaining three years of her five-year term as chief executive. All three of her predecessors as chief executive since the handover of the territory by Britain in 1997 left under a cloud.

The leading candidate to succeed her is not her deputy, Chief Secretary Matthew Cheung, who turns 69 this year and has shown no interest in elective politics.

The top candidate instead is the territory’s third-ranking official, Paul Chan, who serves as financial secretary. Mr. Chan is the political protégé of Leung Chun-ying, a former Hong Kong chief executive who defeated the 2014 Umbrella Movement, and he is part of a clique of business professionals with strong ties to Beijing.

If Mrs. Lam steps down, the most likely rival for Mr. Chan to be appointed by Beijing as the chief executive is Regina Ip, a lawmaker and former security minister who played a key role in unsuccessful national security legislation in 2003.

Mrs. Ip now leads a local political party that emphasizes law and order and is fairly popular, but she is deeply distrusted by democracy advocates.

President Xi Jinping returned to Beijing on Sunday night from a four-day trip for previously scheduled meetings in Kyrgyzstan and Tajikistan. By Monday afternoon, he had not yet made a public appearance, and on Monday night the Chinese government announced that Mr. Xi would make a trip in the coming days to North Korea, his first as the country’s leader.

Wang Yang and Han Zheng — the two of the seven Politburo Standing Committee members who had expressed support for the extradition bill — also laid low on Monday.

Mrs. Lam began an energetic effort to rebuild public support. She gathered presidents and principals from the city’s universities, high schools and elementary schools, as well as local religious leaders, for a large meeting at her official residence.