Harris, 51, has already got the backing of US President Barack Obama and Vice President Joe Biden to be the state's next Senator, brightening her chances to become the first from the community ever to be a member of the Upper House.
She heads into the US Senate election with a considerable lead over fellow Democrat Loretta Sanchez, whose plan to coalesce Republicans and Latinos behind her has not materialised, according to a new poll.
Harris is leading Sanchez, a 10-term congresswoman from Orange, 47 to 23 per cent, among likely voters.
Some 17 per cent remain undecided, and another 13 per cent volunteered that they plan to sit out the contest between two members of the same party. Among those who have already voted, 55 per cent chose Harris, 26 per cent backed Sanchez and 14 per cent said neither, the report said.
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While Sanchez has touted herself as the business-friendly choice for disaffected voters, about one-third of Republicans and 12 per cent of unaligned voters told pollsters they will not cast a ballot for either Sanchez or Harris, it said.
Harris has never trailed since launching her bid in January last year, with her share of the vote increasing seven percentage points since a May poll. She continues to hold advantages in all major regions of the state, and with voters in all age ranges and educational backgrounds, it said.
Harris, who was born in Oakland, California, is the daughter of an Indian mother who emigrated from Chennai in 1960 and a Jamaican American father.
Harris and Loretta Sanchez were vying for their party's seal of approval to replace Senator Barbara Boxer, who is retiring.
If she wins, Harris will make history by becoming the first ever US Senator of Indian-origin.
There have been several Indian-American Congressmen in the House of Representatives, including current member Ami Bera and retired member Dalip Singh Saund, both from California too.