"AJSU has become BJP's 'B' team. Sudesh Mahto is an opportunist who ditched his dedicated workers though they nursed their constituencies expecting tickets (from AJSU)," Soren said at a public meeting at Barhi in the district.
He welcomed disgruntled AJSU leader Sabi Devi and her supporters into JMM during the meeting and announced her candidature from Barhi.
Devi is the widow of AJSU leader Tileshwar Sahu who was gunned down by suspected ultras of the People's Liberation Front of India (PLFI) some months ago.
The AJSU has eight seats with the BJP as per seat sharing understanding.
AJSU's Hatia MLA Naveen Jaiswal had resigned from the party and joined the Babulal Marandi's Jharkhand Vikas Morcha.