Clinton a 'formidable' candidate: Bishop

Hillary Clinton will be a "formidable" presidential candidate, Australia's most senior female politician says.

The former first lady declared herself the Democratic Party's US presidential nominee on Wednesday, and will be the first woman to lead a major party in the race to the White House.

Foreign Minister Julie Bishop said it was a "remarkable achievement" for Ms Clinton, who is expected to come up against Donald Trump as the Republican Party's nominee.

"I know her, I've met her on a number of occasions and she most certainly will be a formidable candidate," Ms Bishop told reporters on Wednesday night.

"But of course the Australian government will work with whomever the American people choose to be the president, in our national interest."

Prime Minister Malcolm Turnbull, who this week called himself "a feminist", said Ms Clinton's success showed "girls can do anything".

"It is a matter for celebration that a woman has been - is about to be endorsed as the presidential candidate of a major - one of the American parties," he told the ABC.