Congress leader DK Shivakumar broke down today as counting leads indicated a big victory for his party in Karnataka. Mr Shivakumar said he had "promised to Sonia Gandhi I will deliver Karnataka".
"I assured Sonia Gandhi, Rahul Gandhi, Priyanka Gandhi and Mallikarjun Kharge that I will deliver Karnataka. I can't forget Sonia Gandhi coming to meet me in jail," Mr Shivakumar, 61, told reporters.
The Karnataka Congress chief, who is a contender for the Chief Minister's job, said: "The Congress office is our temple. We will decide our next step at the Congress office."
He also said he had not slept for three years. "I want to thank my leader Sonia Gandhi. She reposed confidence in me. Since that day I have not slept," he said.
"I thank all leaders in my state including Siddaramaiah," he added, asserting that it was "not my victory alone".
Siddaramaiah, 75, is his main rival in the race for the chief minister's post.
"It's a big victory for the Congress party. The people of Karnataka wanted change. This is a mandate against Prime Minister Narendra Modi," Siddaramaiah said.
The Congress crossed the halfway mark in Karnataka in less than two hours of counting. The party hopes to finish with at least 120 seats, riding on a jump in its vote share. The party appeared to have made big gains at the cost of the Janta Dal Secular (JDS).
The incumbent BJP conceded defeat and said it would return during the Lok Sabha polls next year.
"In spite of a lot of efforts put in by PM and BJP workers, we have not been able to make the mark. Once the full results come in we'll do a detailed analysis. We take this result in our stride to come back in Lok Sabha elections," said outgoing Chief Minister Basavaraj Bommai, who had earlier said he was confident of a BJP victory.