In 926, Li Cunxu, who had established a
Later Tang as its emperor, was killed in a mutiny at the then-capital
Luoyang. Li Siyuan, who had earlier rebelled against him, quickly arrived at Luoyang and claimed imperial title. Zhu Hongzhao became the overseer of the palace technicians (). Later in the year, Li Siyuan launched a general campaign against the rebellious warlord
Wang Du the military governor of Yiwu Circuit (義武, headquartered in modern
Baoding,
Hebei), under the overall command of the general
Wang Yanqiu. Wang Yanqiu believed Yiwu's capital Ding Prefecture () to have strong defenses and therefore would be difficult to attack directly; rather, he wanted to surround the city and put it under siege, to drain out the city's food supplies. Both Zhu and Zhang Qianzhao (), serving under Wang Yanqiu, claimed that Wang Yanqiu was being cowardly, and Li Siyuan, believing them, ordered Wang Yanqiu to attack. Wang Yanqiu's initial attacks, under such orders, resulted in heavy casualties, and he was then able to persuade Li Siyuan to allow him to resume his strategy of starving out the Ding Prefecture defense. He was eventually able to capture Ding in 929, and Wang Du committed suicide. In 930, Meng and Dong, fearful of An's suspicions against them, had allied with each other and rebelled against Li Siyuan's rule. Li Siyuan sent his son-in-law
Shi Jingtang to command the operations against the two circuits, but the operations stalled against the two circuits' defenses. An offered to head to the front to review the operations, and Li Siyuan agreed. On the way to the front, An stopped at Fengxiang. Zhu personally came out of the city to bow to him, and housed An inside his own headquarters. He also had his wife come out to bow to An and to present food to An. An, touched by the gesture, stated, "Libelers had repeatedly accused me, and I almost could not escape. It was only because His Imperial Majesty saw the situation clearly that I still have my clan." After An departed Fengxiang for the front, Zhu immediately submitted a report to Li Siyuan, accusing An of showing anger to the emperor and stating that he was fearful that when An arrived at the front, he would seize command of the army from Shi. He also sent messengers ahead of An, informing Shi of the same thing. Shi, in fear, also sent messengers to Luoyang asking Li Siyuan to recall An. Li Siyuan therefore did so. When An received the recall and headed back to Luoyang, he went first to Fengxiang, but Zhu, this time, refused to receive him into the city at all, causing An, in fear, to try to head to Luoyang as quickly as possible. Li Siyuan, however, gave him no chance to return to Luoyang, but instead commissioned him as the military governor of Huguo Circuit (護國, headquartered in modern
Yuncheng,
Shanxi) without allowing him to return, and subsequently had him killed. Shortly after An's death, Zhu was recalled to Luoyang to again serve as the director of palace affairs. By 933, Li Siyuan's oldest surviving son,
Li Congrong the Prince of Wei, who was generally considered Li Siyuan's likely heir, had made all of the high level officials fearful of him due to his arrogant and violent ways. Then-chiefs of staff,
Fan Yanguang and
Zhao Yanshou, whom Li Congrong had threatened repeatedly, in particular, did not want to remain chiefs of staff, and repeatedly requested to be sent out to the circuits. Li Siyuan was initially resistant, believing that they were abandoning him, but eventually relented, allowing Zhao to become military governor of Xuanwu Circuit (宣武, headquartered in modern
Kaifeng,
Henan) and naming Zhu to replace him. Zhu initially tried to decline the post as well, but Li Siyuan angrily stated, "If people like you all refuse to be by my side, what use was it for me to feed you?" Zhu did not dare to decline further, so took his office. Li Siyuan also bestowed the
chancellor designation
Tong Zhongshu Menxia Pingzhangshi () on him. Shortly after Zhu became chief of staff,
Feng Yun replaced Fan as the other chief of staff. Thereafter, Li Siyuan became extremely ill, but had not yet named an heir. Li Congrong wanted to force his way inside the palace so that the succession would not be diverted from him, but when he suggested the idea to Zhu and Feng, both were resistant of him. Li Congrong therefore decided to fight them with his army. The imperial guards, however, under orders from Zhu and Feng, as well as Kang (who was serving as a commanding general at that time) and the eunuch
Meng Hanqiong, resisted and defeated Li Congrong's army. Li Congrong was subsequently killed. Li Siyuan subsequently agreed to summon Li Congrong's younger brother
Li Conghou the Prince of Song, who was then serving as the military governor of Tianxiong Circuit (天雄, headquartered in modern
Handan,
Hebei), but died before Li Conghou reached Luoyang. When Li Conghou reached Luoyang, the high-level officials, including Zhu, supported him to be emperor. == During Li Conghou's reign ==