NSUI has won the president post after four years while, Akhil Bharatiya Vidyarthi Parishad (ABVP) managed to bag two posts also.
A total of 43 per cent voter turnout was recorded in the DUSU elections.
Speaking to ANI, Congress leader Deepender Hooda said, "We had won three seats but recounting of votes shows ABVP's unconstitutional face. We will go to the judiciary! This is one of the biggest victories for us and we will always support student politics."
"As NSUI won the president and vice-president posts, the ABVP grabbed the Secretary and the Joint Secretary position; this clearly shows that BJP and ABVP have played a dirty politics," he added.
The ABVP held three posts in the outgoing panel.
Meanwhile, Congress president Sonia Gandhi met winning candidates from NSUI outside her residence. The NSUI also held a victory rally at North Campus of varsity.
The NSUI has won the DUSU president's post for the first time since 2012.
Congress vice-president Rahul Gandhi too hailed the Congress ideology and congratulated the union on Twitter.
Earlier in the day, the Congress sent out congratulatory messages after the results were out. Senior Congress leaders Ajay Maken and Sharmistha Mukherjee congratulated the students' wing for winning three seats.
Following the results, the Bharatiya Janata Party (BJP) said it does not see the defeat on two posts in DUSU election as an indicator of party's popularity graph.
The Left Unity swept the polls after a tough fight from ABVP and many students voted for NOTA (None of the above) than NSUI.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)