Well-known union leader Sharad Rao and his supporters tied up with the Sharad Pawar-led Nationalist Congress Party on Thursday.
The move, just before the Lok Sabha election, will give a boost to the NCP, which is facing a tough time after Chhagan Bhujbal's downfall.
"We decided to break with [Defence Minister] George Fernandes because of our ideological differences," Rao, a general secretary of the Hind Mazdoor Kisan Panchayat, said.
Fernandes remains HMKP president, but according to Rao, the office bearers are firmly behind him.
A new rule says that no minister can head unions. Rao said, "George could be replaced long back. He is continuing because for a long time the union did not have its general meeting. That meeting is going to be held very soon and then a new president will be selected."
For many years Rao did not put up any candidates to challenge Bharatiya Janata Party or Shiv Sena candidates. "And on the other hand, Sharad Powar has done many things for us. So for executive of Hind Mazdoor Kisan Panchayat had decided to join NCP."
Rao is considered a big union leader in Mumbai. He heads the Mumbai Mazdoor Union, BEST Worker Union, Auto Rickshaw Union, Mumbai Bidi-Tambakhoo Wyapari Sangh, Taxi Man Union, Gumasta Union and many other outfits.
All these union are controlled by HMKP, which has around 20 lakh register members.