“This is absolutely about rooting out the people Xi perceives as working against him,” said Joseph Fewsmith, a professor at Boston University who specializes in politics among China’s elite.

Image Ling Jihua, at the Great Hall of the People in Beijing in March 2013. Credit... Jason Lee/Reuters

Mr. Ling’s spectacularly lurid downfall began in 2012 when he was demoted following reports that his son had been killed in a high-speed crash driving a Ferrari on a Beijing road. Two female passengers were injured in the accident, and one of them later died. According to party officials, Mr. Ling went to great lengths to cover up the crash, with the families of both women paid enormous amounts of hush money.

The scandal was a major blow to the political rise of Mr. Ling, who instead of being appointed to the Politburo was removed from his positions as director of the party’s Central Committee General Office and as Mr. Hu’s personal secretary. He was given a far smaller post as head of the United Front Work Department, the agency that manages the party’s dealings with China’s ethnic minorities.

Yet even as Mr. Ling’s name continued to appear as head of that agency, a series of investigations that dug deeper into the activities of his relatives and associates spelled impending political doom. The steady, tightening scrutiny was almost identical to the methods used by Mr. Xi to topple other high-ranking officials, including Bo Xilai, a former Politburo member now serving life in prison on corruption charges and Zhou Yongkang, the former domestic security chief and retired member of the Politburo standing committee who was sentenced to life in prison last month. Both were accused of conspiring directly against Mr. Xi.

Although the party has not explicitly accused Mr. Ling of seeking to undermine Mr. Xi, his expulsion from the party, along with the charges against him — bribery and sexual misconduct — are similar to the type of punishments levied against the president’s biggest rivals.