The party was formed in March 2003 by Anandidevi Singh in March 2003, after the Nepal Sadbhavana Party chairman Badri Prasad Mandal had joined the government installed by King Gyanendra.

[1] After the NSP(A) was founded, a Central Working Committee consisting of Durba Prasad Rajbanshi, Kushi Lal Mandal, Gauri Prasad Singh, Bhogendra Thakur, Madhav Prasad Yadav, Dev Narayan Yadav, Renu Yadav, Bishwonath Shah, Ramnarayan Raya, Kritram Pandit, Jaya Narayan Chaurasiya, Govinda Chaudhary, Govinda Tharu, Kasim Ali Siddique and Anil Kumar Jha was elected.

Anandidevi Singh retained the chairmanship of the unified party, whilst Laxman Lal Karna (NSP chairman) became vice chairman of NSP(A).

[1] However, just three months later the party suffered a major split, as Minister for Industry, Commerce and Supply Rajendra Mahato and Laxman Lal Karna formed their own 'NSP(A)' (later renamed 'Sadbhavana Party').

Since Gupta was sacked from the government cabinet, Khushi Lal Mandal vowed to pull NSP(A) out of the Seven Party Alliance.