The ruling BJP on Monday bagged four seats and was leading in eight others as the B S Yediyurappa-led government appeared on course to sweep the bypolls in 15 constituencies and retain a majority.
The opposition Congress and JDS faced a huge setback.
The Congress, which had won 12 of those 15 seats in the previous election, was leading only in two segments -- Hunsur and Shivajinagar.