In December 1995, after serving in CYL for over ten years, Ling was transferred to General Office of the Communist Party of China, and continued his work in political theory. Between 1994 and 1996 Ling obtained an "on-job master's degree" in commercial management at Hunan University. In June 1998, he was promoted to head of research office of the General Office (中央办公厅调研室主任). In December 1999, Ling was appointed as deputy director of General Office. Later, he also served as the deputy chief of the General Office in charge of the Central Institutional Organization Commission, and chief of staff of the Office of General Secretary Hu Jintao.
On July 20, 2015, Ling was expelled from the Communist Party of China, and was arrested to face criminal proceedings. Ling's case received significant media attention, since he was the most prominent political figure expelled from the party since criminal proceedings were initiated against former Politburo Standing Committee member Zhou Yongkang. In the party's disciplinary dossier against Ling, he was accused of "violating political discipline, violating political rules, violating organizational discipline, and violating confidentiality discipline." He was further accused of taking in large bribes, aiding in the business interests of his wife, sexual misconduct with "numerous women", and illegally obtaining party and state secrets.
Jiaozuo is noted for its blast furnaces and machine construction industries. The total GDP of the city in 2017 was 234.28 billion yuan, an increase of 7.4% over the previous year. Among them, the added value of the primary industry was 13.733 billion yuan, up 4.6%; the added value of the secondary industry was 13.841 billion yuan, up 6.7%; the added value of the tertiary industry was 81.143 billion yuan, up 9.1%. The per capita GDP reached 65,936 yuan. The three industrial structures changed from 6.4:59.3:34.3 of 2016 to 5.9:59.5:34.6.link