Soaking in the moment of glory, Gopalan Balachandran, maternal uncle of Senator Kamala Harris, on Saturday night said he told her niece a day earlier that she was "going to win" to become the next US vice president.

Democrat Joe Biden defeated incumbent Republican President Donald Trump in the closely-fought presidential election.

Harris, 56, who is of Indian origin, has become the first-ever woman vice president-elect of the US. She will also be the first Indian-origin, first Black and first African American vice president of the country.

Delhi-based Balachandran said he was feeling "proud and happy", describing Harris as a fighter.

"Biden-Harris victory is what we wanted to see. And, given the numbers, I told Kamala yesterday (Friday) that she is going to win," he told PTI when asked if the counting process made him tense.

Biden, the 77-year-old former vice president, will become the 46th president of the United States.

"This election is about so much more than Joe Biden or me. It's about the soul of America and our willingness to fight for it. We have a lot of work ahead of us. Let's get started," Harris tweeted.

She was born to two immigrant parents: a Black father and an Indian mother. Her father, Donald Harris, was from Jamaica, and her mother, Shyamala Gopalan, a cancer researcher and civil rights activist from Chennai.

In an interview to PTI in August, Balachandran had said that Harris's nomination as the vice presidential candidate was a "historic moment", but it was not a surprise at all for him.

Harris's maternal uncle had said that she would script many firsts if she won and expressed the hope her top-level position would give Indians in the US "greater access" in interacting with the US administration.