But he also assured that his party would remain with the BJP in these elections.
A lawyer by profession, Kovind had also been BJP Scheduled Caste Morcha chief (1998-2002) and president of the All-India Koli Samaj.
Communist Party of India-Marxist leader Sitaram Yechury said Kovind "was chief of the RSS's Dalit branch" and "somewhere it was a political fight or contest".
The BJP on Monday announced the name of 71-year-old Kovind, a low-profile Dalit leader and a two-term BJP Rajya Sabha member, as its nominee for the president's post.
Prime Minister Modi, who on Twitter said Kovind would make "an exceptional President", personally talked to Congress leaders Sonia Gandhi and Dr Manmohan Singh to seek their support for the BJP's nominee.
"If elected, Kovind will ensure that Modi has a friend in Rashtrapati Bhavan". "He has a lot of experience and knowledge", said Swamy. With an illustrious background in the legal arena, he said, Kovind's knowledge and understanding of the Constitution will benefit the nation. He devoted his life to public service & worked for poor and marginalised. I am bound to pay my respect to him (Kovind) after declaration of his candidature for the post of the President India, the chief minister said.
The Left parties are keen on the opposition putting up a candidate because they see the Presidential election as an "ideological battle" and the NDA candidate as an RSS-backed man. BJD Chief Naveen Patnaik has already confirmed the support for BJP, the regional parties down south TRS, AIADMK (both fractions) and YSR Congress have pledged their support for the NDA Nominee.
Mayawati, in her remarks to the media, said: "We are not against Kovind's nomination".
West Bengal Governor Keshari Nath Tripathi has been given additional charge as Governor of Bihar. President Pranab Mukherjee has also accepted his resignation as the Governor of Bihar. "We were not expecting this from the ruling party", he said.
Senior BJP leader M. Venkaiah Naidu spoke to party veterans L.K. Advani and Murli Manohar Joshi. "But they informed us after announcing this decision so there is no scope for consensus now. we were not expecting this from the ruling party".
The NDA government's decision to field Bihar Governor Ramnath Kovind as its presidential candidate has seemingly caught the opposition parties by surprise.
The leaders of the Opposition will meet on Thursday to decide their candidate.