The ruling Congress-led United Democratic Front on Thursday retained the Thiruvalla assembly seat in Kerala with Elizabeth Mammen Mathai of the Kerala Congress (M) defeating her nearest rival Verghese George of the Janata Dal (S) by a margin of 4,669 votes.

The by-poll had assumed added significance in the backdrop of the factionalism within the Congress, which had resulted in the party losing the Ernakulam Lok Sabha seat in a by-poll two months back.

Mathai won with a reduced majority, beating the twin-challenge posed by the CPI-M led Left Democratic Front and the Karunakaran faction of the Congress. The reduced margin may be a result of the factionalism within the Congress.

The by-election in the heartland of central Travancore was caused by the death of Elizabeth Mammen's husband Mammen Mathai who had won the seat last time with a margin of over 10,000 votes to make it to the assembly for the third time in a row.