Even as exit poll projections revise their estimates of outcome in Tamil Nadu, I depend on my understanding of the state's voting behaviour in the past. As this is one state which can decide who can form the Government, let us look at it closely. In fact, the revised estimates have surprised a columnist sympathetic the BJP to the extent that he has now conceded that Manmohan Singh forming the Govt. is now a certainty (Management of expectations). According to the revised estimates of CNN-IBN and NDTV exit polls, the DMK-Congress combine is likely to sweep the polls.
I have been interested in the voting behaviour of voters in different States. One aspect of this interest has been to find out why the voters in Tamil Nadu have always given a decisive verdict in favour of one party or combination or the other. One consequence of this trend has been a single party government in the State, even as they voted one of the regional parties to power. When it comes to the Lok Sabha election, however, the party or alliance which is allied to a national party likely to form the Government at the Centre has been the beneficiary of the mandate in the State.
Let us look at the past trends. In 1998, the BJP and the AIADMK had an electoral understanding and swept the polls. In 1999, AIADMK's withdrawal of support, bringing down the Government at the Centre did not go down well with the TN voters. The BJP-DMK alliance swept the polls in 1999. Despite many grounds for withdrawal of support, the DMK kept the support going till 2004, and it is only on the eve of the Lok Sabha elections, the party switched sides, and had an alliance with the Congress. Although the DMK switched alliances, it did not destabilise the Government at the Centre. The DMK-Congress alliance was rewarded with a decisive mandate. The BJP and AIADMK had an alliance in 2004, but the voters did not rightly think that the BJP was in a position to form the Government at the Centre, and even if it was, it did not choose a reliable partner, considering what she did in 1999. Analysts overestimate the arithmetic factor in Tamil Nadu, by suggesting that whoever has a bigger alliance, in terms of number of partners, is likely to sweep the polls. But this is a very limited understanding, and simplistic because it does not explain whether the voters are aware that they are voting in a Lok Sabha election. My alternative thesis explains this rather satisfactorily.
In 2009, the AIADMK did not have the slight advantage it had in 2004, when it aligned with the BJP. Instead it aligned with the Left and the smaller parties, who according to the TN voters, are unlikely to form the Government on their own at the Centre. Therefore, the exit poll projections in TN, contrary to what the opinion polls said, are reliable. Many analysts have said this election had no national issues or that each State voted on State issues. Even as I don't agree with this analysis at the all-India level, at least in TN,the voters have always been distinguishing between state assembly and Lok Sabha elections. Well, this is my tentative analysis. I will stand revised, and probably look for alternative answers if I am proved wrong tomorrow.
UPDATE: With the trends available (4 p.m.May 16), I don't see the need to revise my analysis of why the TN voters voted the way they did. Even if it is not a sweep, it is an overwhelming mandate in favour of the Congress-DMK alliance. In the comments section, Srinivasan Ramani rightly suggests that the DMDK's inroads might have made a sweep impossible. AIADMK aligned only with the BJP in 2004, and the TN voters correctly did not see the combination capable of forming a stable Government at the Centre. One can discern one more factor. Ever since Jayalalithaa destabilised a Government at the Centre (in 1999), the AIADMK-led alliance has not received a favourable mandate in the Lok Sabha elections. As the TN voters favour stability at the Centre, they appear reluctant to give a mandate to the AIADMK in the Lok Sabha elections, even if they are willing to let AIADMK to return to power in the State.