Congress leader and UPA chairperson Sonia Gandhi will file her nomination for the Rae Bareli Lok Sabha seat of Uttar Pradesh on Thursday. Sonia Gandhi, who has been representing the seat since 2004, will contest against Dinesh Pratap Singh, who had recently joined the Bharatiya Janata Party after leaving the Congress. The Samajwadi Party and the Bahujan Samaj Party have not fielded any candidate in the Congress bastion. Rae Bareli goes to polls on May 6 in the fifth phase of the general election. Sonia Gandhi had won the seat in 2004, 2006 (bypolls), 2009 and 2014. In 2014, there were 15.94 lakh voters in the constituency and the poll percentage was 51.73 per cent, in which Sonia Gandhi had got 5,26,434 votes. Since 1957, the Congress has won the seat 19 times, including three by-elections, and lost the seat only three times - 1977, 1996 and 1998. In 1977, after Emergency, Bharatiya Lok Dal's Raj Narain had defeated the then prime minister Indira Gandhi. In 1996 and 1998, BJP candidate Ashok Kumar Singh won the seat. The constituency has five assembly segments - Bachhrawan, Harchandpur, Rae Bareli, Sareni and Unchahar. The seat was represented by Feroze Gandhi, Indira Gandhi, Arun Nehru, Sheila Kaul and Satish Sharma in the past.