BEIJING - With just over a month until Chinese New Year, taxi driver Mr Huang is excited about his Spring Festival vacation in Thailand. "Bangkok first, then Phuket. A little quality time with my wife and daughter," Huang said.

Huang never had the "luxury" of spending quality time with his family until three years ago.

"Spring Festival used to be one of the busiest time of year for me," he recalled, "People would book my car for the day and I would drive them across the city with my trunk full to bursting with bags of all sizes. I could earn hundreds of yuan a day," he said.

"Gifts they were -- or so they revealed, accidentally, of course. They were quite secretive about it," Huang jeered, "Corruption."

These day-trip gifters stopped using his services three years ago, coincidentally not long after the launch of Xi Jinping's anti-graft campaign.

"At first, I thought the dust would settle and the campaign would fade away, and New Year's 'routine' would return soon enough. I was wrong," he said.

Four years into the campaign, which has caught numerous corrupt "tigers" and "flies" -- senior officials and low-ranking cadres - the sweeping drive spearheaded by Xi is showing little sign of losing steam.

HUNTING TIGER, SWATTING FLIES

Xi has shown greater grit and determination to fulfill his promise on stamping out notorious corruption ever since he took the helm of the world's largest political party in November 2012.

He has warned his fellow Communist Party of China (CPC) cadres of what he saw as endemic corruption eating away at the Party's authority and effectiveness.

"[And] there are also many pressing problems within the Party that need to be resolved, particularly corruption, being divorced from the people, going through formalities and bureaucratism caused by some Party officials," he said. "The whole Party must stay on full alert."

Early the next month, the first senior official fell from grace. A former deputy Party secretary of Sichuan Province, Li Chuncheng held the ominous title of being the first tiger to be caught by the campaign.

Many have followed in the ensuing four years.

The sheer scope of the investigation and the fact that being a member of the upper echelons did not make you exempt explains why Xi's campaign has won him popularity among the public.

According to the head of the CPC Central Committee for Discipline Inspection (CCDI), Wang Qishan, more than one million people have been punished for violating CPC and government rules since November 2012. In total, 222 centrally administered officials have been investigated, with 212 receiving disciplinary punishment.

Among the tigers felled by the campaign were Zhou Yongkang, a former member of the Standing Committee of the Political Bureau of the CPC Central Committee; Bo Xilai, former Party chief of Chongqing Municipality; Xu Caihou and Guo Boxiong, two former top generals and both vice chairmen of the Central Military Commission; Ling Jihua and Su Rong, former vice chairmen of China's top political advisory body.

As Xi once put it, "All people are equal before the law and regulations, and the enforcement of such rules allows no privilege or exception."

The hunt has even expanded overseas as China strives to hunt down its economic fugitives.

Over 2,400 fugitives have been brought back to China from around 70 countries and regions across the globe since the launch of operation "Sky Net" in 2014, with 8.5 billion yuan (around $1.2 billion) recovered.

CAGE OF REGULATIONS

Many say this anti-graft drive will be a hallmark of Xi's time in office, as he has proved that the campaign is far from short-lived.

One of the more recent tigers caught is former deputy Party chief of Beijing Lyu Xiwen. She was indicted for accepting bribes worth $2.73 million and taking advantage of her official positions to help others obtain government funds and land for construction from 2001 to 2015.

Her trial followed a string of other high-ranking officials taking the stand last month. In one case, Zhu Mingguo, former head of the political advisory body in the southern province of Guangdong, was sentenced to death with a two-year reprieve for accepting bribes and holding "a huge amount" of assets from unidentified sources.

Flies also continue to be swatted, as evidenced by terse, and almost regular, reports posted by courts, procurators and the CCDI.

In fact, some observers have gone as far to suggest that the anti-corruption campaign is the "new normal."

They also noted, however, that for the campaign to become a lasting political legacy, more needs to be done.

Catching those that have already broken the law will not eliminate corruption, Xin Ming from the Party School of the CPC Central Committee said.

"Only when there is an effective system that ensures officials are unable to be corrupt, corruption can be purged," he said.

Cheng Wenhao, a professor of Tsinghua University's School of Public Policy and Management and director of its Center for Anti-corruption and Governance, agreed.

"The anti-corruption campaign of the last several years has successfully deterred public officials. The primary task for the next step is corruption prevention," he said.

"It involves multiple tasks, including reducing public power, making power operation more transparent, minimizing the discretionary power of officials, among others. These measures will reduce corrupt opportunities caused by the willful exercise of excessive public power, thus making power abuse activities less feasible," Cheng said.

Authorities have said there are three phases in the fight against graft: the first stage is to ensure officials don't dare to be corrupt, then institutionalizing the drive and perfecting the legal framework so officials aren't able to be corrupt, and lastly, promoting an ethical and moral compass so that officials won't want to be corrupt.

There are signs that China now has at least one foot in the second phase. Over the past year or so the drive has become less visible and dramatic. The heyday of the tiger hunting when senior officials and generals seem to be falling one after another appears to have past.

Rather, the earlier blitz attacks have now given way to a less dramatic, but perhaps far more significant, war to institutionalize the corruption purge.

This gear shift is a prelude to deeper changes, as measures are rolled out to ensure effective institutions to prevent corruption from occurring at all.

On various occasions, Xi has said power must be held within a "cage of regulations" for corruption to be successfully eradicated.

In a study session attended by members of the Political Bureau of the CPC Central Committee in April 2015, Xi stressed the importance of laws and regulations in the anti-corruption campaign.

The key measure for the anti-corruption struggle is to improve the supervision and restriction mechanism for power, he said.

ALWAYS ON THE ROAD

Much of the Party's efforts have been poured into such institutional and mechanism reform.

Measures have been formulated to name and shame officials who interfere in judicial cases.

Pilot programs on supervision committees have also been launched in Beijing and the provinces of Shanxi and Zhejiang. The ultimate goal is to build a national anti-graft organ that could mobilize more anti-corruption resources.

Anti-corruption also featured heavily at the sixth plenary session of the 18th CPC Central Committee, which elevated Xi to the core of the Party leadership.

Two new documents on the Party's code of conduct were approved at the plenum, namely the norms of political life in the Party under the current conditions -- an update from a 1980 document -- and the regulation on intra-Party supervision, promising an emphasis on preventing paid promotions, and "zero tolerance" for corruption at all levels.

But according to the three-stage theory of the anti-corruption campaign, however, the success of this campaign ultimately lies on the third stage where officials don't want to be corrupt.

"When officials have less power and fewer opportunities to abuse their power, and face great penalty for doing so, they will be less willing to cross the line," said Cheng Wenhao.

This is much more difficult than changing institutions, according to Xu Guangjian, vice dean of Renmin University's School of Public Administration.

"This will take considerably longer time," he said.

His words were echoed by Xin Ming, who noted that the anti-graft drive is a long fight, not just in China, but in all other parts of the world too.

The CPC has been in power for 67 years. Xi and the Party need to think about the long term, he said.