NCP MLC Sanjay Kaka Patil from Tasgaon in Maharashtra resigned from his post alleging "harassment" by a minister from his party and joined the BJP.
The development is being viewed as a huge embarrassment for Maharashtra Home Minister R R Patil, as the NCP MLC was from his constituency.
BJP is likely to field Sanjay as a Lok Sabha candidate from Sangli seat in western Maharashtra.
Senior BJP leader Gopinath Munde, who welcomed Sanjay in the party fold, said making leaders defect the NCP is his target. He also claimed two more senior leaders from the Sharad Pawar-led party would cross over to BJP in coming days.
"To get leaders from NCP is our main target. We are after NCP," Munde said while addressing a press conference announcing Sanjay's entry into BJP.
Munde said his aim was to bring back those leaders who had left the BJP to join NCP.
Earlier in the day, Sanjay announced his resignation in the Legislative Council, alleging he was fed up with "harassment" by a NCP minister. He then tendered his resignation as an MLC and as an NCP member, to the Council chairman Shivajirao Deshmukh.
"I have been facing problems at the party level. A minister in the party is constantly harassing me. He is trying his best to end my political career," he alleged in the House.
Munde alleged that Sanjay quit NCP due to R R Patil.
"The NCP legislator had to desert Sharad Pawar because of R R Patil. He had so much of respect and affection for Pawar. I had invited him to join BJP in 1995, but he refused. He did not even accept my offer of ministerial berth in the then NDA government," said the deputy leader of BJP in Lok Sabha.
"Sanjay kept the NCP chief (Sharad Pawar) and his nephew (Ajit Pawar) in the loop about his plight but even after that they failed to give him justice," Munde said. Meanwhile, Sanjay said he would "expose" home minister Patil at an appropriate time.