He launched it after paying his respects to Jayalalithaa and MGR at their memorials at the Marina beach here.
Speaking to reporters after launching the party flag, Madhavan, clad in a traditional white khadi shirt and dhoti, said he has the support of 'true Amma followers' and that he would give Deepa a key post if she decided to join his party.
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"I have the support of true Amma (Jayalalithaa's) followers. If Deepa decides to join our outfit, I will give her key post (in the party)", he said.
Deepa had launched 'MGR Amma Deepa Forum' on February 24, coinciding with Jayalalithaa's anniversary.
Madhavan, who was involved in forming it, had quit the party last month, alleging "there is a lot of dominance of some evil forces".
Deepa's forum also faced a controversy after she faced opposition over the appointment of some office bearers.
Hoping to taste success through Jayalalithaa's legacy, Deepa decided to contest the RK Nagar bypoll, which was later cancelled by Election Commission, citing use of money power to influence voters.
In the affidavit filed by her for the RK Nagar bypoll, Deepa had never mentioned about Madhavan nor any of her family members.