DMK president M K Stalin Sunday greeted United Progressive Alliance chairperson Sonia Gandhi on her election as leader of the Congress Parliamentary Party.
"I extend my hearty greetings to respected Annai (mother) Sonia Gandhi," he said in a Facebook post.
Congress leaders in Tamil Nadu usually refer Sonia Gandhi as "Annai Sonia" as a mark of respect.
Stalin said "no power" can remove the Congress party's excellent work from the good hearts of the Indian people.
The Dravidian party chief said Congress was the "permanent guarantee for pluralism, secularism, social justice and equality enshrined in the Constitution".
Also, the poor, middle-class and marginalised sections
reposed their faith on Congress party, he said.
Sonia Gandhi was elected leader of the Congress Parliamentary Party (CPP) on Saturday in Delhi. Former prime minister Manmohan Singh proposed her name and it was unanimously endorsed by all party MPs.