- O Panneerselvam took over as Chief Minister after Jayalalithaa's death
- He vacated the position for party chief VK Sasikala on Sunday
- Sasikala will soon take oath, depending on Governor's availability
It is not known yet if Mr Pannerselvam's resignation has been accepted. Mr Rao, who is the Maharashtra Governor and holds additional charge of Tamil Nadu, is currently in Maharashtra. Ms Sasikala is yet to take oath as the Chief Minister. Sources said the ceremony will be scheduled as soon as the Governor becomes available.
Mr Panneerselvam, 65, has stepped into the breach twice earlier after Ms Jayalalithaa, as the Chief Minister, was arrested on charges of corruption. This time, after her death in December, he was the party's automatic choice for the top job. Party insiders, though, had hinted that it was a stop-gap measure, saying it was the party chief who should also head the government. After Ms Sasikala accepted the post of the party general secretary, there have been calls for Mr Panneerselvam to step down.
On Sunday, Ms Natarajan - who is not an elected member of the assembly and had never held any post in the party - said Mr Pannerselvam had a key role to play in her decision to head the government.
"It was Panneerselvam who had first persuaded me to become the chief minister and general secretary as well when Jayalalithaa passed away," news agency Press Trust of India quoted her as telling party legislators.