Rubuta ci gaba don wannan sakin layi - Soosaithasan ya tsaya a matsayin dan takarar Jam'iyyar Liberation Front na Tamil United a Mannar a zaben 'yan majalisa na 1977. Ya lashe zaben kuma ya shiga majalisar. Ya yi aiki a matsayin shugaban Kwamitin Lissafin Jama'a. Soosaithasan da duk sauran 'yan majalisar TULF sun kaurace wa majalisar daga tsakiyar 1983 saboda dalilai da yawa: suna karkashin matsin lamba daga mayakan Tamil na Sri Lanka don kada su ci gaba da zama a majalisar bayan wa'adin su na shekaru shida; Kwaskwarima na shida ga Kundin Tsarin Mulki na Sri Lanka ya bukace su da su rantse rantsuwa ba tare da wani sharadi ba don tallafawa wata ƙasa daban; da kuma Black Yuli
rikicin da har zuwa 3,000 Tamils aka kashe da Sinhalese mobs. Bayan watanni uku na rashi, Soosaithasan ya rasa kujerarsa a Majalisar a ranar 22 ga Oktoba, 1983.