The ruling BJP on Thursday conceded defeat in Rajasthan, where the Congress won the Mandalgarh Assembly seat and was poised to grab the Ajmer and Alwar Lok Sabha seats.
Rajasthan BJP chief Ashok Parnami told reporters: "We respect the people's mandate and we will analyse the reasons for our defeat. I am taking responsibility for the defeat."
The Congress drew a blank in Rajasthan in the 2014 Lok Sabha polls.
The Congress maintained a significant lead in Alwar and Ajmer parliamentary seats in Rajasthan and it moved ahead in Mandalgarh assembly seat where the BJP was leading initially, as per trends by afternoon available in the counting of votes for the bypolls.
Earlier in the day in Alwar, Congress candidate Karan Singh Yadav was leading by 39,826 votes over his nearest rival, Jaswant Yadav from the BJP, after 15 rounds of counting. Yadav had garnered 1,63,489 votes.
In Ajmer, Congress' Raghu Sharma was maintaining a lead of 23,882 votes over BJP candidate Ram Swaroop Lamba.
In Mandalgarh, where the BJP was maintaining a lead in the beginning, Congress' Vivek Dhakad moved ahead with a lead of 1,146 votes
After 11 rounds of counting, he received 42,201 votes while BJP candidate Shakti Singh Hada got 40,555 votes.
Congress dissident Gopal Malviya, who was running as an independent, garnered 22,310 votes.
The BJP had won all the 25 Lok Sabha constituencies in the state in the 2014 general elections.
The party, which wrested power from the Congress in 2013 in Rajasthan, had 161 MLAs in the House of 200. It had strategised raising the tally of seats to 180 in the assembly polls due this year end.