However, soon there would be other challengers to Li's potential succession to Sui. Li Yuan, having nominally become a regent over Yang You, briefly considered the possibility of taking Luoyang himself, sending his sons Li Jiancheng and Li Shimin to Luoyang, claiming to be aiding it, but the Sui generals in Luoyang refused to acknowledge Li Yuan's authority and did not respond. Li Mi himself briefly engaged Li Jiancheng and Li Shimin, but after a minor skirmish, both sides disengaged, and Li Jiancheng and Li Shimin soon withdrew back to Chang'an. A larger threat loomed for Li Mi, however, as late in spring 618, a coup led by Yuwen Huaji (Yuwen Shu's son) at Jiangdu killed Emperor Yang, and Yuwen Huaji, after declaring Emperor Yang's nephew Yang Hao emperor, began to lead the elite Xiaoguo Army () back north, toward Luoyang, posing a major threat to Li Mi's hold over the region.