Born in Japanese-era Taiwan, Chai earned his master's and doctorate degrees in the United States.

He was a pro-democracy advocate and founded the Association for a Plebiscite (Chinese: 公民投票促進會; pinyin: Gōngmín Tóupiaò Cùjìnhùi) and Formosa Television.

[3] In 1960, Chai went to the United States and studied at the University of Tennessee, where he earned his master's degree in political science.

In 2005, he urged the Ministry of Education to get rid of contexts of "aboveboard Chinese" (堂堂正正的中國人; a Chinese nationalistic term imposed by the Chiang Kai-shek regime after World War II) from the back cover of elementary school workbooks.

"[9][10] Despite the fact that Chai was endorsed by renowned pharmacologist Chen-Yuan Lee, he lost the DPP chairmanship election in 1996.

[3] However, the resignation of Su Tseng-chang as DPP chairperson in 2005 led to Chai's decision to run again.

He was endorsed by vice president Annette Lu and foreign minister Mark Chen.

Former Secretary-General of the Presidential Office Yu Shyi-kun won with over 54% of the votes while Chai received 36%.