After the formation of the First United Front in 1923, Chiang Kai-shek, holder of the party's military power, felt hemmed in by the Soviet advisors who had control over KMT policies and the Communists who had infiltrated the KMT. After the 2nd KMT National Congress in 1926, Chiang came under attack by KMT leftists led by Wang Jingwei. After the "Zhongshan Incident," Chiang aimed to settle the score with the CPC and KMT leftists through the "Resolutions on the Rectification of Party Affairs." Since he was still subject to numerous attacks and provocation during the Northern Expedition, Chiang launched the violent April 12 Purge in 1927 in Shanghai. Taking the period between the 2nd KMT National Congress and the April 12 Purge as its scope of study, this paper, based on Chiang's diaries, explores Chiang's attitude toward the KMT leftists and Wang on the eve of the party purge.