He founded the Democratic Action Alliance [zh] in 2004 and was elected to the National Assembly in 2005, but resigned on the first day to protest the parliament's formation.

[4] The organization demonstrated against several of Chen Shui-bian's policies, namely legislative approval of a weapons procurement deal with the United States,[5][6] and amendments to the Constitution of the Republic of China pertaining to the powers of the National Assembly.

[10] In 2006, Chang and the Democratic Action Alliance asked that the Kuomintang initiate recall proceedings against party member Hsu Tsai-li, who had been found guilty of corruption while serving as mayor of Keelung.

[12][13] Following the election of Ma Ying-jeou to the presidency in 2008, Chang drafted a "Basic Agreement on Peaceful Cross-Strait Development" to be negotiated with China, published in the Journal of Current Chinese Affairs in 2010.

"[25][26][27] While Hung served as Kuomintang chairwoman, the party passed a resolution supporting the establishment of the Sun Yat-sen School [zh].

[30] The Sun Yat-sen School worked with the 800 Heroes veterans' organization and the National Civil Servant Association, among others, to petition in support of a question regarding pension reductions on the 2018 Taiwanese referendum.