Washington | Presumptive Democratic presidential candidate Joe Biden has taken the historic decision to make Kamala Harris, a proven political battler who becomes the first black woman on a major US party ticket, his running mate.

Ms Harris, a 55-year-old former rival for the Democratic nomination who clashed with Mr Biden last year as the party's contest began in earnest, will stand alongside the former vice-president on Wednesday (Thursday AEST) in Delaware to launch their joint ticket.