Himachal Pradesh's Mandi parliamentary constituency recorded nearly 48 percent voter turnout at 4 p.m., about an hour before the close of polling, after a sluggish start in the by-election Sunday morning.
"The voter turnout ultimately could be slightly higher than 55 percent, as people have now queued up at a number of polling stations, and they will all be allowed to cast their votes," an electoral officer told IANS here.
"The voter turnout was just seven percent in the first one hour, but by 11 a.m. it rose to nearly 17 percent and 25 percent by 1 p.m.," he said.
Voting began at 8 a.m. and there was no report of any delay in polling due to malfunctioning electronic voting machines (EVMs), he said.
A total of 11,24,786 voters will cast votes in two phases and decide the fate of four candidates, including two independents. The main contest is between the ruling Congress and the opposition Bharatiya Janata Party (BJP).
However, voting in the landslide-hit Kinnaur district, part of the constituency, will be held June 27. It has 52,361 voters.
The vote count will be held simultaneously June 30.
The Congress has pitted Pratibha Singh, former MP and wife of six-time Chief Minister Virbhadra Singh against the BJP's former minister and sitting legislator Jai Ram Thakur.
The by-poll was necessitated after Virbhadra Singh relinquished the seat following his election to the state assembly December 2012.
The chief minister and his family cast their votes in Rampur, some 120 km from the state capital, in the morning.
Poll officials said in the 2009 general elections, the Mandi constituency saw 61.42 percent votes polled. At that time, the BJP was in power in the state.
The Mandi constituency, which includes Kullu, Mandi and some areas of Chamba and Shimla districts, besides the tribal-dominated assembly constituencies of Kinnaur and Lahaul and Spiti, is one of the biggest in the country.