Antonio Costa, known as the 'Gandhi of Lisbon' for his frugal lifestyle, has his roots in the former Portuguese colony in India where his grandfather was born and his father spent most of his life.
A popular mayor of Lisbon, the 52-year-old socialist was chosen as Portugal's prime ministerial candidate by the main Opposition Socialist Party for next year's polls.
"The only victor today is the Socialist Party...This is the first day of our future (parliament) majority," he said after defeating party leader Antonio Jose Seguro on Sunday.
He is also set to take over as party leader following Seguro's resignation.
Costa, who served as justice and interior minister in previous socialist governments and as a European Parliament deputy before being elected mayor in 2007, won nearly 70 per cent of the vote.
Costa is the son of Orlando da Costa, who wrote essays on Nobel laureate Rabindranath Tagore.
The Mozambique-born writer spent most of his youth in Portuguese-ruled Goa where his father, Luis Afonso Maria da Costa, was born.
He was a descendant of Hindu families from the Gaud Saraswat Brahmin community which converted to Catholicism during the Portuguese colonial era.
Born Antonio Luis Santos da Costa, the Lisbon-based politician has spoken of strengthening ties with India in the past with Portugal as an "Atlantic hub for business".
Costa is known to many as Babush - the Konkani word for boy - and is admired for his lifestyle reflective of the Portuguese-Goan concept of "susegad" or chilled out and tolerant.
As Lisbon mayor, he moved his office to the Mouraria neighbourhood, which was earlier notorious for drug trafficking and prostitution and is now transformed as an upcoming construction hub.
Opinion polls put the socialists ahead of the Social Democratic party of Prime Minister Pedro Passos Coelho in next year's polls.