In 742, after the death of the chancellor Niu Xianke, Li Shizhi succeeded Niu as "Zuo Xiang" () -- the head of the examination bureau of government (門下省, "Menxia Sheng") and a post considered one for a chancellor; he was also created the Duke of Qinghe. He served alongside Li Linfu, and they fought over control of government, although since Li Shizhi was not a deep thinker, Li Linfu was able to find ways to damage him. For example, on one occasion, Li Linfu told Li Shizhi that there were gold deposits at Mount Hua that could be mined—and Li Shizhi, as Li Linfu intended, then proposed to Emperor Xuanzong to mine the gold deposits. Li Linfu then pointed out that pursuant to Taoist principles, he believed that a mine at Mount Hua would damage Emperor Xuanzong's health, thus bringing imperial displeasure on Li Shizhi. In another incident, in 745, with Li Shizhi also serving as the minister of defense and Emperor Xuanzong's son-in-law Zhang Ji () serving as deputy minister and whom Li Linfu also disliked, Li Linfu had some 60 officials at the minister of defense accused of corruption, and then coerced confessions out of them by torture, intending to use this to discredit Li Shizhi and Zhang, although neither was punished. However, subsequently, Li Linfu was able to accuse several officials friendly with Li Linfu—Huangfu Weiming (), Wei Jian (), Pei Kuan (), and Han Chaozong—and get them demoted or exiled. Li Shizhi, in fear, offered to resign the chancellor position, and in 746 was removed from his chancellor post, becoming an advisor to the new crown prince (Li Ying having been forced to commit suicide in 737) Li Heng. He wrote a poem in which he lamented that after he was removed, not even his family and friends were visiting him.