California's Indian-American Attorney General Kamala Harris, a "good friend" of President Barack Obama, has thrown her hat into the ring for the 2016 race to replace fellow Democrat veteran Barbara Boxer in the US Senate.

"I will be a fighter for the next generation on the critical issues facing our country," pledged Oakland, California-born Harris, 50, the state's first Indian-American and first African American top law officer announcing her run on her website Tuesday.

"I will be a fighter for middle class families who are feeling the pinch of stagnant wages and diminishing opportunity," added the daughter of an Indian mother and Jamaican-American father.

"I will be a fighter for our children who deserve a world-class education, and for students burdened by predatory lenders and skyrocketing tuition. And I will fight relentlessly to protect our coast, our immigrant communities and our seniors," Harris said.

Harrison's mother Dr Shyamala Gopalan is a breast cancer specialist who emigrated from Chennai in the 1960s while her father Donald Harris is an economics professor at Stanford University.

Hours after Harris announced her run, billionaire environmentalist Tom Steyer said he would decide soon whether to take on the follow Democrat in the November 2016 election.

Steyer and Harris would be among the most formidable contenders for Boxer's seat, along with former los Angeles Mayor Antonio Villaraigosa, who has said he is "seriously considering" a run, according to CNN.

Harris, the former district attorney of San Francisco who was just re-elected to her second term as attorney general, was the first to formally declare her candidacy since Boxer announced last week that she would not run for re-election in 2016.

Harris' position was strengthened Monday when lt. Gov. Gavin Newsom bowed out of contention. Newsom, 47, is reported to be interested in running for governor when Jerry Brown faces term limits in 2018.

If Harris wins, she would be the first ever Indian-American in the 100-member US Senate.

Three Indian-Americans have been elected to the US House of Representatives: Dalip Singh Saund, Bobby Jindal and Ami Bera, who was re-elected for his second term last November.

There are also currently two US governors of Indian origin - Bobby Jindal and Nikki Haley - both Republicans are said to be mulling presidential runs in 2016.
Obama last year caused a bit of a stir when he called Harris "by far the best-looking attorney general."

He later called long time friend Harris to apologise for saying: "She's brilliant and she's dedicated, she's tough. She also happens to be, by far, the best-looking attorney general ... It's true! C'mon." Harris graciously accepted the President's apology.