The entry of Sarathkumar, belonging to the powerful Nadar community, could help the BJP.
Veteran actor R Sarathkumar has merged his party All India Samathuva Makkal Katchi (AISMK) with the BJP in Tamil Nadu, days after entering an alliance with it.
The merger took place at his erstwhile office in Chennai when the state BJP Chief Annamalai visited.
"I took this decision after so much of introspection. I was apprehensive what my cadre would say. I am glad they were persuaded. Instead of seeking alliance and demanding seats, I thought why not offer full support to Prime Minister Narendra Modi," Mr Sarathkumar told NDTV.
The 69-year-old was made a Rajya Sabha MP by the DMK in 2001. After a stint with the AIADMK, he launched his own party, AISMK, in 2007. In 2011, he was elected MLA to the Tenkasi assembly constituency in alliance with the AIADMK.
Welcoming him to the party, Mr Annamalai said, "Sarathkumar would now have a national role in mainstream politics".
The entry of Mr Sarathkumar, belonging to the powerful Nadar community, could help the BJP draw the support of the community, particularly in the southern districts.
Some say it's a double-edged sword and his decision could backfire too in the Dravidian heartland. The development saw a mixed response in his party.
In a video NDTV cannot independently verify, a teary eyed woman said, "It is hard to believe but I'd accept Sarathkumar's decision". Another man literally abused the actor politician and was shooed away.
The BJP which has less than 3 per cent vote share in Tamil Nadu has not yet found a major ally after the exit of AIADMK. So far, GK Vasan's TMC only has joined hands.
The party is in talks with PMK and late actor Vijayakanth's DMDK.