"It has been three months now since the merger of EPS-OPS faction. Months are passing by, what about hearts?," Mr Maitreyan, who is a member of Rajya Sabha, said in his Facebook post.
Queried about his remarks, Mr Maitreyan, who was in the OPS faction, said he had already expressed his views and did not wish to say anything more.
Senior party leaders KP Munuswamy and Manoj Pandian refused to comment on Mr Maitreyan's remarks.
However, when asked if all the promises made prior to the merger were met, Mr Munuswamy said, "Differences inside any party are a routine affair and they will be resolved internally according to the convenience of stakeholders."
Deputy Chief Minister Panneerselvam after meeting Prime Minister Narendra Modi in October had told reporters that he had no differences with Chief Minister Palaniswami and all the decisions were taken inclusively.
Following party supremo Jayalalithaa's death in December last year, two factions led by Mr Panneerselvam and VK Sasikala were formed. Later, a large group of legislators led by Chief Minister Palaniswami revolted against Ms Sasikala, who is in jail in a corruption case, and announced merger of the two factions.