Lai, vice president and the ruling Democratic Progressive Party's (DPP) presidential candidate, has almost consistently led opinion polls ahead of an election taking place amid increased Chinese pressure on Taiwan to accept Beijing's sovereignty claims.
Vincent Chao, spokesperson for the Lai campaign, declined to comment on Hsiao's role but said an announcement on a running mate would be made on Monday.
Randall Schriver, the former U.S. assistant secretary of defense for Indo-Pacific Security Affairs, described Hsiao as a "good partner in promoting U.S.-Taiwan relations."
The DPP-led government says only Taiwan's people can decide their future, and has repeatedly offered talks with Beijing but been rebuffed.
Like Lai, Hsiao is detested by China, which has on two occasions placed sanctions on her, most recently in April, saying she is an "independence diehard".
Persons:
Lai Ching, Lai, Democratic Progressive Party's, Hsiao, Vincent Chao, Ivan Kanapathy, Randall Schriver, Chen Shui, Ben Blanchard, Yimou Lee, Michael Martina, Gerry Doyle
Organizations:
Democratic Progressive, APEC, Asia, U.S . National Security Council, Reuters, Georgetown University, Patriot, Pacific Security Affairs, U.S, DPP, Taiwan Affairs Office, Thomson
Locations:
TAIPEI, United States, Washington, Taiwan, San Francisco, U.S, Taipei, Ukraine, China, Beijing, Japan