A possible third front, comprising non-Congress and non-Bharatiya Janata Party (BJP) partners, got a further boost on Monday with the ruling All India Anna Dravida Munnetra Kazhagam (AIADMK) in Tamil Nadu formally announcing its alliance with the Communist Party of India-Marxist (CPM) for the ensuing Lok Sabha polls.br br The AIADMK's electoral tie-up with the CPM comes a day after the party announced its pre-poll alliance with the Communist Party of India.br br The alliance was clinched after a delegation headed by CPM General Secretary Prakash Karat called on AIADMK supremo and Tamil Nadu Chief Minister J Jayalalitha at her Poes Garden residence.