"We lost badly in the Lok Sabha elections in the state due to our alliance with the JD-S. Had the party contested alone, it would have won 15-16 seats," Moily told reporters at Chikkaballapur.
The former Union Minister lost to B.N. Bachhe Gowda of the BJP in the Chikkaballapur parliamentary seat by 1.8 lakh votes.
Claiming that the tie-up with the JD-S to contest jointly in the general elections was a mistake, Moily said the Congress lost more than its ally, as it won only one of the 21 seats.
"Our party could retain only one (Bangalore Rural) of the 9 seats it had won in the 2014 elections, which was the highest from any state in the country," he said.
Moily also blamed the JD-S for his defeat, accusing its leaders and cadres of not supporting him in campaign and securing their party votes for him as a joint candidate.
While the JD-S contested 7 seats, it also won only one seat (Hassan). The BJP won 25 of the 27 seats it contested, while an Independent it supported one more.
Besides Moily, Congress veterans and former Union Ministers like Mallakarjun Kharge and K.H. Muniyappa had also lost, while from the JD-S saw its supremo and former Prime Minister H.D. Deve Gowda lose.
As a split verdict in the May 2018 state assembly elections resulted in a hung house, the Congress and JD-S entered into a post-poll alliance to form a coalition government so as to keep the BJP out of power.
( With inputs from IANS )