Former Punjab Chief Minister Amarinder Singh on Tuesday resigned from the Congress and sent a seven-page letter to party President Sonia Gandhi. He named his party the Punjab Lok Congress."I have today sent my resignation to Congress President Sonia Gandhi ji, listing my reasons for the resignation. 'Punjab Lok Congress' is the name of the new party. The registration is pending approval with the Election Commission of India. The party symbol will be approved later," Amarinder Singh informed in a tweet.Singh had quit as the chief minister in September after a power tussle with state Congress chief Navjot Sidhu.