 Ponnambalam was one of the ACTC's candidates in Jaffna District at the 1989 parliamentary election but the ACTC failed to win any seats in Parliament.Initially Ponnambalam did not support the separatist agenda espoused by Sri Lankan Tamil militant groups and worked closely with the Sinhalese politicians, co-authoring Sirimavo Bandaranaike's manifesto in 1988.But as the Sri Lankan Civil War progressed he grew disillusioned and distrustful of Sinhalese politicians and took a more nationalistic stance.