杜如晦
Meanwhile, Li Chengqian was losing favor with Emperor Taizong over his wastefulness and favor for games rather than study. He also suffered from a foot illness that the nature was not specified in historical accounts. Li Tai began to have ambitions on displacing his older brother as crown prince, and a number of officials, seeing this as an opportunity, began to congregate around Li Tai, causing the government to divide into Li Tai's faction and Li Chengqian's faction. In 642, in order to dispel rumors that he was about to replace Li Chengqian with Li Tai, Emperor Taizong made Wei Zheng, then ill, Li Chengqian's senior advisor, but that failed to stop the rumors. Meanwhile, Li Tai's chiefs of staff, Wei Ting (韋挺) and Du Chuke (杜楚客, brother to the deceased chancellor Du Ruhui), were making plans for Li Tai to enhance his reputation and defame Li Chengqian, and the public began to perceive Li Chengqian negatively.