Donald Trump and Ben Carson lead the Republican race for the US presidential nomination, with the two non-politicians together accounting for more than half the support from potential voters, a new poll showed yesterday.

The Washington Post-ABC News poll also found that Hillary Rodham Clinton, dogged by a controversy over her use of a private email server while serving as secretary of state, has steadily lost support over the past two months.

Though she still leads the Democratic field, potential voters gave her less than 50 percent support for the first time in Post-ABC surveys, with her popularity dropping most among white women.