Caught between the tough lines they have pursued on the nuclear deal, both Congress and Left have now turned to allies to mediate to save the coalition from a seemingly irreconciliable situation. A day after DMK boss and Tamil Nadu chief minister M Karunanidhi warned that BJP could return to power exploiting the differences in the ruling combine, CPM chief Prakash Karat and CPI secretary D Raja met him in Chennai on Sunday pleading for his intervention to break the impasse.