Sangma, former Speaker of Lok Sabha, along with his daughter and MP Agatha Sangma called on Modi at the latter's residence in Gandhinagar.
Announcing support of NERPF, which comprises ten regional parties, to Modi, he said "Modi is one step closer to becoming prime minister".
Sangma is the president of National People's Party (NPP).
The NERPF had fielded candidates on 21 out of 25 seats of the North East region.
Sangma had formed NPP after resigning from NCP, of which he was one of the founder members, after the Sharad Pawar-led party had refused to support him in his Presidential bid in 2012.
Sangma's daughter Agatha had served as union minister of state for Rural Development in UPA-II government.