Within the
Democratic Progressive Party, Yu Tian is allied with
Yu Shyi-kun. He is also known for his support of former president
Chen Shui-bian. Yu ran for
New Taipei 3 in 2008, and defeated Kuomintang incumbent
Chu Chun-hsiao by approximately 2,000 votes. Chu filed an unsuccessful lawsuit in an attempt to annul the election results. A separate case was brought against Yu supporter Wang Ying-lan, who was charged with making threats to the opposition. Wang was later released on bail. In November 2008, Yu and other DPP politicians publicly protested
Ma Ying-jeou's meeting with
Association for Relations Across the Taiwan Strait Chairman
Chen Yunlin. The next year, Yu's DPP membership was suspended because he had failed to fulfill a fundraising quota. In 2010, Yu was named to
Tsai Ing-wen's New Taipei mayoral campaign team. Though there was speculation that Yu would not receive DPP backing in a reelection bid, Yu was listed fourteenth on the Democratic Progressive Party's proportional representation party list, and expected to win. During the campaign, Kuomintang politicians accused Yu and others of gambling, and in response, Yu charged them with defamation. The Taiwan Competitiveness Forum regarded Yu Tian as a controversial figure prior to the start of his first legislative term. During his first term, Yu was ranked highly by the Citizen Congress Watch. In 2018, Yu was the only candidate to run in elections for the DPP chapter leadership in New Taipei. After
Gao Jyh-peng was removed from office, Yu Tian was named the DPP candidate for by-elections held in March 2019. Yu won 56,888 votes, and defeated Kuomintang candidate as well as independent Su Ching-yen. Yu took office on 21 March 2019. Yu was reelected to a full term in 2020. ==Personal life==