The bypoll, necessitated following the death of former Speaker and Congress leader G Karthikeyan, is a crucial test for both the Fronts as the Assembly poll is only an year away.
The Campaign got momentum with the presence of Congress leaders including Chief Minister Oommen Chandy, Home Minister Ramesh Chennithala, KPCC President V M Sudheeran and 92-year-old CPI-M veteran and opposition leader V S Achuthanandan.
Achuthanandan has virtually stormed the segment near the state capital with his usual campaign style.
For UDF, which came to power with a wafer thin majority of two MLA's in 2011 and is riding on the slogan of "development and care", the result is widely considered as a referendum on the performance of the government.
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Chandy had said that the poll result would be a recognition to the development works and welfare measures undertaken by the government.
Congress, in a bid to gain "sympathy wave", has nominated 33-year-old K S Sabarinath, son of Karthikeyan as its candidate.
The poll outcome is also significant for CPI-M veteran and former state secretary Pinarayi Vijayan, who heads the LDF campaign, as he is tipped to be the party's Chief Minister candidate if LDF comes to power after next assembly polls.
Karthikeyan had represented Aruvikkara, known as Aryanadu before delimitation, since 1991. He had won the seat last time with a margin of over 10,000 votes by defeating RSP candidate Sreedharan Nair.