Nearly 500 people, including former BJP MLA Dilip Moran, from various political parties and social groups joined the opposition Congress on Wednesday, while almost an equal number of people joined the party ahead of the assembly polls due next year.
Mr Moran, who was a BJP legislator from Doom Dooma, joined the Congress in presence of its state chief Ripun Bora in Guwahati.
BJP leader Niranjan Nath also switched sides to the opposition party.
The Asom Gana Parishad's (AGP) Bakkkar Ali Ahmed and Ismail Hussain joined the Congress along with 50-odd party workers.
Petros Basumatary of the Bodoland People's Front (BPF) too joined the same party.
The AGP and the BPF are constituents of the ruling BJP-led coalition.
Abdul Khandakar and Shahjahan Ali of the All India United Democratic Front (AIUDF) joined the Congress with over 100 supporters. These two leaders unsuccessfully contested the 2016 Assembly polls.
Apart from them, a number of singers, actors, dancers, music composers and others joined the Congress.
On the other hand, nearly 500 Congress workers switched allegiance to the BJP in Nagaon in presence of party MLA Rupak Sarmah.
"The Congress workers are frustrated at their party's alliance with the AIUDF. We have been telling it from the beginning that if the tw opposition parties join hands, the BJP will be the maximum gainer," Mr Sarmah said.
The election to the 126-member Assam Assembly is due in April next year.
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