Senator Kamala Harris announces US presidential run

"The future of our country depends on you and millions of others lifting our voices to fight for our American values. That's why I'm running for president of the United States," the senator from California said in a video posted on Twitter.

Ms Harris joins Senator Elizabeth Warren of Massachusetts, Hawaii congresswoman Tulsi Gabbard, New York Senator Kirsten Gillibrand and former housing secretary Julian Castro, among others, either in the race or exploring a run for the 2020 Democratic nomination.

Nearly 22 months before the 2020 election, the battle for the White House is already firming up, as Americans begin to assess who might be the opposition party nominee to challenge Mr Trump for control of the White House.