The former Bihar Governor and a Dalit leader Kovind was declared NDA's presidential pick on Monday by the BJP president Amit Shah.
Kovind filed his nomination at Parliament House.
Meanwhile, a confident Bharatiya Janata Party (BJP) on Friday, while maintaining that the NDA Government's presidential nominee Ramnath Kovind will win with majority, said that the Congress Party is using Meira Kumar as a "sacrificial goat" in this election.
I will strive to keep President's post above party politics: Ram Nath Kovind.
Process of filing nomination begins.
"Will accompany Ram Nath Kovindji as he files his nomination papers", Modi tweeted. PM Narendra Modi, BJP president Amit Shah by Ram Nath Kovind's side.
Kovind looks set to get more than 61 per cent of the votes, and the final tally may increase depending on how some still-undecided regional parties vote, BJP sources said.
Kovind will be pitted against the opposition candidate Meira Kumar, who will file her nomination on June 27. Kumar, who has also been a cabinet minister in the UPA dispensation, is backed by the Congress, Left parties, RJD, SP, BSP and the Trinamool Congress.
Ever since I became governor, I don't belong to any political party: NDA Prez candidate Ram Nath Kovind.
The election for the next President of India is to be held on July 17 as President Pranab Mukherjee will demit the office on July 24.