Ramamurthy Naidu, brother of Andhra Pradesh chief minister and Telugu Desam Party leader N Chandrababu Naidu, on Monday joined the Congress.
Ramamurthy met Congress president Sonia Gandhi at her Parliament House office and expressed willingness to work for the party, to which she immediately agreed, sources said.
Ramamurthy has had a strained relationship with his elder brother ever since the TDP leadership cold-shouldered him following his defeat in the 1999 assembly polls.
In Hyderabad, the TDP made light of the development saying he was not a member of the party, as he had failed to renew his membership.