The decision is being seen as a blow to Congress.

A former Minister in the Tarun Gogoi government in Assam, Himanta Biswa Sarma, met BJP president Amit Shah in New Delhi and signalled that he would be joining the party in two or three days.

With elections due in Assam next year, Mr. Sarma’s move is being seen as a blow to the Congress.

“I met Amit Shahji to discuss certain outstanding issues with regard to Assam, and expressed my willingness to work under the strong leadership of the BJP. I shall be formally joining the party in the next few days,” Mr. Sarma said. He has sent his resignation from the primary membership of the Congress to the All India Congress Committee.

Mr. Sarma was once an important part of the Gogoi Ministry but fell out with the Chief Minister over competing ambitions and business interests. Mr. Gogoi removed him from the Cabinet more than a year ago. His joining the BJP has been speculated upon for long, with one senior party member from the State, Pradyot Bora, quitting the BJP in protest against Mr. Sarma’s joining the party.

It is not yet clear what the local leadership of the BJP, especially Union Sports Minister Sarbananda Sonowal, has to say about the matter. Mr. Sonowal has been projected as the party’s face in the next Assembly polls in every public meeting addressed by Mr. Shah till now.

The BJP is hopeful of wresting power in Assam, where it won a handsome seven of the 14 Lok Sabha seats in the 2014 polls.