BEIJING (NYTIMES) - Across China, police officers, judges, prosecutors and feared state security agents have been studying former Communist Chairman Mao Zedong's methods for political purges, absorbing them as guidance for a new Communist Party drive against graft, abuses and disloyalty in their ranks.

The campaign is shaping up as a sharp tool for the Communist Party leader Xi Jinping to bolster domestic discipline as he prepares for a leadership shake-up in two years as well as continuing strife with the United States and other countries.

Officials in China's law-and-order apparatus have been ordered to "drive the blade in" and "scrape poison off the bone", setting aside personal loyalties to expose wayward colleagues.

The model for this "education and rectification" programme, leaders have told them, should be Mao's drive of the 1940s, which cemented his dominance over the party from a base in the city of Yan'an.

"Root out the harmful members of the herd," Mr Chen Yixin, a chief enforcer of the campaign, said at a kickoff meeting last month. "Root out 'two-faced people' who are disloyal and dishonest to the party."

Such mobilisation sessions have proliferated across China - in courts, police headquarters, prison administrations and the secretive Ministry of State Security, which controls the country's main civilian surveillance and spy forces.

They and other law-and-order agencies come under the Central Political and Legal Affairs Commission, a bastion of party power, along with the military. President Xi calls the command of the security system the party's "knife handle", a menacing term taken from Mao.

The genuflections to Mao, who remains revered by the Communist Party, reflect Mr Xi's desire to use the campaign to help fireproof his and the party's power against possible turbulence.

"The Yan'an rectification was about obeying Mao in everything, and that's the biggest signal from learning from Yan'an this time," Mr Deng Yuwen, a former Chinese editor for a Communist Party newspaper, said in an interview from the United States, where he now lives. "The core goal of cleaning up the political and legal system is also to obey Xi in everything."

Soon after Mr Xi came to office eight years ago, he unleashed a wave of anti-corruption cases that have felled hundreds of senior officials. The former chief of the domestic security apparatus, Zhou Yongkang, was sentenced to life in prison on corruption charges in 2015.

Despite those efforts, experts and recent Chinese studies said the party leadership is still struggling to manage its hydra-headed bureaucracy of police forces, security agencies, courts, prosecutors and prisons. Early last year, the party issued new rules to tighten top-down control of the system. Studies by Chinese researchers have said that fragmentation and rivalry between agencies remain problems.

Months of protests in Hong Kong last year and the pandemic crisis this year seem to have reinforced Mr Xi's push for iron authority right down to local police stations.

"Resolutely put absolute loyalty, absolute purity and absolute dependability into action," the minister of public security Zhao Kezhi said this month while inspecting enforcement of the campaign in northeast China.

China's leaders appear most worried about lower- and mid-level police officers and legal officials, said professor of law Qin Qianhong at Wuhan University in central China. A separate campaign since 2018 to break alliances between crime gangs and officials reinforced senior officials' worries that their local forces remained compromised by corruption, he said.

"Although China's investigations of official criminality and corruption have taken down a bunch of people, the main political-legal structure has not been replaced, for the most part," Prof Qin said. Invoking Mao's Yan'an purge did not mean that officials were applying its harsh methods, he said.

"It's to show that this rectification must be taken seriously," he said. "But Yan'an was about establishing a core leader and nurturing loyalty, and that must be followed."

The campaign is scheduled to last until early 2022, the cusp of a Communist Party congress that will install a new cohort of central officials and, most likely, extend Mr Xi's time in power. Publicity about the campaign has described local officials studying Mr Xi's writings and speeches in indoctrination classes deep into the night.

Teams of investigators have already plucked out cadres accused of corruption and other abuses. In the first week of the campaign, 21 officials from the public security or legal systems came under investigation, officials announced.

"It suggests a continued push on Xi Jinping's part to remake China's coercive apparatus into a force that is entirely politically responsive to his direction," said associate professor Sheena Chestnut Greitens from the University of Texas at Austin who studies Chinese policing and has written a forthcoming paper about the drive to clean up China's law-and-order bureaucracy.

Mr Xi wants "to push his authority downward throughout the lower levels of the political-legal system" before the party congress in 2022, she said.

The campaign has also confirmed the rise of Mr Chen, a 60-year-old official who over the past couple of years has handled a succession of politically tricky tasks. He has also led the drive against local crime protection rackets and seized hold of efforts to stifle the coronavirus epidemic in Wuhan in February, when the city where the outbreak began appeared overwhelmed.

"These high-profile roles have certainly given him a lot of name recognition and the opportunity to build a base of following," academic Ling Li, an expert on Chinese politics and law at the University of Vienna, said in e-mailed answers to questions. "It looks like he is prepared for bigger roles."

Some analysts have seen this campaign as an effort by Mr Xi to drive out factional opponents. But the breadth of the actions indicate that Mr Xi wants to shake up the entire hierarchy, said Mr Christopher Carothers, a postdoctoral fellow at the University of Pennsylvania who studies anti-corruption policies in China.

"Xi's vision of a highly controlled society demands a strong apparatus to enforce that control; corruption is a threat to that," he said. "Even if there hasn't been any new spike in disloyalty or abuses in these institutions, the Communist Party leadership may still not be satisfied that they are effectively handling a growing and quickly changing mission."