He is the second prominent leader, after Union Shipping Minister G K Vasan, to opt out of the poll race.
A statement from the former Tamil Nadu Congress Committee president's office said Thangkabalu has not filed a request with the state unit to seek a ticket to contest and only three local leaders had nominated him.
The statement recalled that Thangkabalu had quit as TNCC chief in 2011, owning moral responsibility for the party's loss in the assembly election, in which the Congress could win only five seats out of the 63 it contested in alliance with the DMK.
"Thangkabalu had informed the Congress high command that he would not fight the general election," it said.
He had conveyed his decision to senior Congress leaders Gulam Nabi Azad and Mukul Wasnik, who look after the Congress’s affairs in Tamil Nadu, saying, "New faces shall get a chance".
Thangkabalu, who was humbled in the Salem Lok Sabha constituency in 2009, is the second prominent leader after Vasan to opt out of the race, in the backdrop of the Congress failing to strike an alliance.
There is also speculation that former minister Jayanti Natarajan is not keen to contest from Sriperumbudur and Union Finance Minister P Chidambaram wants his son Karti to contest from his bastion Sivaganga.
Image: K V Thangkabalu
Sheela Says: Narendra Modi wants Varanasi, and he will get it!
'Rahul has not yet come into mainstream politics'
VOTE: Rediff Pulse of the Nation Poll!
NDA will win Lok Sabha race, but will need more allies: Poll
NCP to take on alliance partner Congress in Goa