In a blow to the Congress ahead of assembly polls in five states, former Union Minister RPN Singh quit the party today, amid reports that he is switching to the BJP, in a huge blow to the party just weeks before the Uttar Pradesh election.

RPN Singh was among the party's biggest leaders in Uttar Pradesh. He tweeted his resignation letter addressed to Sonia Gandhi.

"Today, at a time, we are celebrating the formation of our great Republic, I begin a new chapter in my political journey. Jai Hind," he wrote, sharing his brief letter.

Earlier today, speculation began when Singh changed his Twitter bio and dropped "Congress". "My motto India, First, Always," reads his bio, which earlier said AICC (All India Congress Committee) in-charge.

This is the second big exit from the Congress in Uttar Pradesh after Jitin Prasada quit last year. Mr Prasada joined the BJP and later became a minister in the Uttar Pradesh government led by Yogi Adityanath.

RPN Singh was an MP from the Padrauna in Uttar Pradesh.