Tharoor facing twin challenge in Thiruvananthapuram

That would explain why CPI zeroed in on Abraham, who belongs to the numerically-strong Nadar community, to be its candidate for the seat. A doctor by vocation, Abraham is also a member of the Church of South India, to which the vast majority of the Nadar community in the area belongs.

He is also the director of a medical college run by the church.

Rajagopal, and Tharoor, both belong to the Nair community, which has a presence as strong as that enjoyed by Nadars in the area.

Now, if LDF's calculations work out, then things may be easy for Tharoor. Last time, the CPI candidate secured 2.26 lakh votes. This, according to party strategists, is a solid Left vote bank and Abraham could get through by the addition of a good chunk of Nadar votes.

They also point out how, in 2009, BSP candidate Neelalohithadasan (now in JD-S) who, too, belong to the Nadar community, polled 80,000 votes contesting as an Independent.

The Left would also hope that a portion of the Nair votes, and to a certain extent, the votes of the Ezhava community, will be divided between Tharoor and Rajagopal.

But Congress has rejected that logic. The party contends that the results of elections are not determined by caste and religion alone.

"The outcome of elections is decided by politics, issues and the stature of the candidate. All these are in favour of Tharoor," says Mohan Kumar, District Congress Committee (DCC) president.

Fighting hard to defend the seat against the backdrop of the cloud cast by his wife Sunanda Pushkar's death, Tharoor has accused rivals of dragging his personal sorrow into the public domain for their narrow electoral ends.

LDF raked up the issue well before the campaign started, forcing Tharoor to approach Election Commission against some LDF leaders, accusing them of having made humiliating comments in public.