Tamil Maanila Congress leader B S Gnanadesikan, who is a close confidante of the party's chief G K Vasan, recently wrote a letter of apology to Congress president Sonia Gandhi for quitting the party in 2014, a move observers say is a disguised plea for re-entry.

"It was my bad luck that I could not meet (you) last year but kept my decision away from you to which I regret," he said in the two-page letter.

Gnanadesikan inquired about Gandhi's health and regretted not making his reasons for leaving the All India Congress Committee clearer to her.

"It was a mistake: not meeting you and explaining to you the reasons for my decision to quit the AICC and join the TMC,' said Gnanadesikan in his letter which observers say is an indirect plea seeking readmission into the Congress.Gnanadesikan's departure from the TMC, if it comes about, will be a political jolt to G K Vasan; it would also make be the second such loss to the party after S R Balasubramaniam joined the All India Anna Dravida Munnetra Kazhagam.