Tens of thousands voted on Saturday in the by-election to the Kerala assembly in Aruvikara in a triangular contest involving the Congress, the CPI-M and the BJP. Election officials said 51.30 percent of the 184,210 electorate had voted by 1.00 p.m. The election followed the death of Kerala assembly Speaker G. Karthikeyan in March. He had represented the constituency for 24 long years. There are a total of 16 candidates in the fray and 184,210 voters -- up from 164,884 in 2011 when Karthikeyan won by over 10,000 votes. The ruling Congress has fielded Karthikeyan's 31-year-old son K.A. Sabarinathan, while the Communist Party of India-Marxist has nominated 67-year-old former speaker and minister M. Vijayakumar. The Bharatiya Janata Party has put up its regular warhorse, O. Rajagopal, 85. On Saturday, all three candidates expressed confidence of winning the election. Sabarinathan called the Aruvikara electorate his "extended family". Vijayakumar said the electorate was waiting to give a lesson to the Oommen Chandy government. Rajagopal said the people of Kerala were sick and tired of both the main political fronts headed by the Congress and the Communist Party of India-Marxist, and they "definitely vote for a change". On Saturday, the photos of the candidates were affixed on the Electronic Voting Machines -- for the first time in India to eliminate confusion among voters.