Both the major Dravidian parties have been winning the elections alternately since 1989 and AIADMK taking the lead in bringing all major opposition parties under its umbrella has made the contest a much closer one than ever before.
DMK has retained its seven-year old ally Congress, considered to be the third largest party in the state, besides the most backward Vanniars based Pattali Makkal Katchi, Dalit-based Viduthalai Chiruthaigal Katchi, Kongu Makkal Katchi (KMK) and the IUML.
For its part, the AIADMK has aligned with the actor-turned politician Vijaykant''s DMDK, the second largest constituent of the front, the Left parties and some minor parties, including Manitha Neya Makkal Katchi, a Muslim outfit.
The DMK front claims that the presence of PMK and VCK, has given their front an upper hand in the northern parts of the state, where Vanniyars and Dalits formed over 70 per cent of the electorate.
Also, in DMK's calculations, the alliance with the KMK would give it an edge over the AIADMK in the western districts, considered a bastion of Jayalalithaa's party.
The AIADMK claims that the presence of DMDK, said to have a larger following among the Vanniyar community, would neutralise the PMK's effect in the northern belt and its traditional vote bank in the southern and western districts would give a big boost to the combine.