A poor performance will be a big loss of face for the AIADMK chief as her party members have been terming her the next prime minister.
In the case of the DMK, a decent show is important for bargaining for positions at the centre - in case of a fractured verdict.
Similarly, the political future of DMDK's Vijaykant hinges on the party winning a considerable number of seats and joining a BJP-led government in Delhi, experts say.
The Congress fought a lone battle with a couple of its leading commanders like P. Chidambaram and G.K. Vasan deciding to sit out.
For parties like PMK and MDMK, the election is crucial as they have to secure at least six percent votes to have the status of a recognised political party.