Teoh represented
Bagan in the
Dewan Rakyat from 1986 to 1990, and was state assemblyman for Pengkalan Kota from 1982 to 1990 and Paya Terubong from 1990 to 1995. He was leader of the state chapter at the time that DAP made a serious bid to take over the Penang state government at the
1990 Malaysian elections. For that campaign, dubbed Tanjong 2, the party formed an alliance with the Umno splinter party Semangat 46 as part of the
Gagasan Rakyat coalition. However, even though party chief
Lim Kit Siang defeated incumbent Chief Minister
Lim Chong Eu in Padang Kota, DAP only narrowly failed to win the election, securing 14 out of the state's 33 seats. Teoh fell out with other DAP leaders in 1998, and joined fellow opposition party
Parti Keadilan Nasional, later known as Parti Keadilan Rakyat with a number of DAP members. ==Retirement and death==