The cause of the sudden death of the recently resigned Chinese Prime Minister has been revealed

Former Chinese Premier Li Keqiang has died at the age of 68. He was considered the PRC’s “number two leader” for 10 years before being sidelined by Xi Jinping.

Former Chinese Premier Li Keqiang died suddenly at the age of 68, Chinese state media reported. Li suffered a heart attack and died in Shanghai early Friday morning, according to Chinese news agency Xinhua.

“Comrade Li Keqiang, who had been vacationing in Shanghai in recent days, suffered a sudden heart attack on October 26 and, after all efforts to resuscitate him failed, died in Shanghai at ten minutes past midnight on October 27,” state broadcaster CCTV reported.

Observers say Li will be remembered as a champion of freer markets and a champion of China’s poorer citizens, and as a symbol of a political alternative sidelined by the autocratic rise of Xi Jinping, The Guardian writes.

Li served as premier of the People’s Republic of China – the second-highest position in China’s political system – for ten years, from 2013, until he was replaced by new premier Li Qiang in March.

“No matter how international winds and clouds change, China will steadily expand its opening up,” Li Keqiang said in March during his last public appearance at a news conference. “The Yangtze and Yellow Rivers will not flow backward.”

In a sign of how authorities handled the news of his death, some social media users reported that they were prohibited from posting videos of his remarks, The Guardian notes, recalling that in the past, mourning events after the death of former leaders have been used by people to express dissatisfaction with the current government.

On Friday morning, Li Keqiang’s death became a top topic on Weibo, a Chinese social network similar to Twitter. Many commenters expressed shock and grief, but the comments were on posts that mostly focused on news and government accounts.

Li was believed to be popular among the Chinese people and officials even after his removal as prime minister, The Guardian writes. Viewed as former leader Hu Jintao’s preferred successor as president, he was overlooked when the leadership chose Xi Jinping in 2012. Li Keqiang and Hu Jintao were both members of a faction rivaling Xi Jinping in the Chinese Communist Party, but its supporters have faded into the background in recent years as Xi has consolidated his personal power and promoted his supporters to key positions, the British publication continues.

“His ten-year tenure also showed a general failure to prevent the political decline of Lee and his mentor Hu Jintao’s Communist Youth League power base,” said Wen-ti Sun, a China expert at the Australian National University.

The son of a local official in poor Anhui province, Li was sent to the countryside to work as a laborer during the Cultural Revolution. He then earned a law degree from Peking University, where he became interested in Western and liberal political theory, translating a book on the law of a British judge, according to classmates.

But he became more orthodox after joining the ranks in the mid-1980s, working as a bureaucrat while his former classmates protested in Tiananmen Square in 1989 and rising through the ranks through his involvement in Komsomol activities.

In 1998, he became China’s youngest governor appointed to the populous central province of Henan, where he later became party secretary. After serving as party chief of northern Liaoning province, he was appointed vice premier under former premier Wen Jiabao from 2008 to 2013, overseeing economic development and macroeconomic management.

The politician rose to prominence internationally in part thanks to the “Li Keqiang Index,” a term coined by The Economist to informally measure China’s economic progress. It was based on a leaked conversation between Li and an American diplomat when Li was a party chief in Liaoning. Lee reportedly said the province’s GDP figures were “unreliable” and suggested a clearer picture could be gleaned from data on electricity consumption, rail freight and bank lending.

Li was considered a proponent of economic reform and spoke from time to time about China’s economic and social problems. However, he has largely toed the party line, especially after Xi Jinping tightened his grip on power.

During his farewell tour of ministries earlier this year, Li Keqiang renewed calls for economic reform, and videos of him visiting some departments and offering warm greetings were later censored on Chinese social media.

Adam Ni, an independent Chinese political analyst and author, described Li as “a premier who found himself impotent as China took a sharp turn away from reform and opening up.”