Buuxi weedha soo socota: 14-kii Maajo 1972-kii ITAK, All Ceylon Tamil Congress (ACTC), Ceylon Workers 'Congress, Eelath Thamilar Otrumai Munnani iyo All Ceylon Tamil Conference waxay aasaaseen Jabhadda Midaysan ee Tamil, oo markii dambe loo beddelay Jabhadda Xoreynta Midaysan ee Tamil (TULF). Sampanthan wuxuu ahaa murashaxa TULF ee Trincomalee doorashadii baarlamaanka ee 1977. Wuxuu ku guuleystay doorashada wuxuuna galay baarlamaanka. Sampanthan iyo dhamaan xildhibaanada kale ee TULF waxay ka soo baxeen baarlamaanka badhtamihii 1983 sababo dhowr ah awgood: waxay ku jireen cadaadis ka yimid maleeshiyaadka Tamilka ee Sri Lanka si aysan baarlamaanka ugu sii joogin wax ka badan muddada caadiga ah ee lix sano ah; Wax ka badalka lixaad ee Dastuurka Sri Lanka wuxuu ka dalbaday inay ku dhaaraan dhaar si shuruud la'aan ah u diidaya taageerada dowlad gooni ah; iyo
Rabshadihii Black July oo ay ku dhinteen ilaa 3,000 oo Tamil ah oo ay dileen kooxo Sinhalese ah. Kadib saddex bilood oo maqnaansho ah, Sampanthan wuxuu lumiyay kursigiisii baarlamaanka 7dii Sebtember 1983. Sampanthan wuxuu u shaqeeyay sidii qasnadaha wadajirka ah, madaxweyne ku xigeenka iyo xoghayaha guud ee TULF.