刘武周
Meanwhile, an intense rivalry had developed between Li Jiancheng and Li Shimin, as while Li Jiancheng had some contributions toward Tang's reunification of China, Li Shimin had been the one defeating and capturing the major rivals Xue Rengao, Liu Wuzhou, Dou Jiande, and Wang Shichong, causing him to possess the greater reputation among the army. Li Yuanji, who was also often relied on by Emperor Gaozu as a general, supported Li Jiancheng in this rivalry, and often pushed Li Jiancheng toward a more hardline position against Li Shimin, wanting to be crown prince when Li Jiancheng would become emperor. Li Jiancheng and Li Yuanji had better relations with Emperor Gaozu's favored young concubines than Li Shimin did (as their mother Duchess Dou had died before Tang's establishment), and those concubines helped rehabilitate Li Jiancheng's standing before Emperor Gaozu, causing him to no longer consider making Li Shimin crown prince instead, as he considered at one point.