The head of an organization that has monitored women in US politics for more than 20 years has hailed the "history-making" selection of Senator Kamala Harris as Joe Biden's Democratic running mate in the 2020 presidential election, but said more needs to be done to ensure gender equality in high office.

Harris, who is also California's former attorney-general, would be the first female vice-president if Biden defeats United States President Donald Trump in November

"There is still an entrenched stereotype of what a successful vice-president candidate looks like in this country, because for hundreds of years it has been a straight white man," said Amanda Hunter, the director of research and communications at the Barbara Lee Family Foundation, a nonpartisan organization aimed at advancing women's representation in politics.

Harris, who is also California's former attorney-general, would be the first female vice-president if Biden defeats United States President Donald Trump in November.

Hunter said that there is an "imagination barrier" when it comes to having a woman vice-president, "not to mention a woman president ... Senator Kamala Harris has the opportunity to throw out the rule book and chart her own course."

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Harris' nomination is only the third time in US history that a woman has been nominated as a presidential running mate. And she breaks even more ground because she is the first black and Asian-American woman to get the role.

Kathleen Dolan, chair of the University of Wisconsin-Milwaukee's political science department, said:"The situation of women in American politics has changed significantly since 1984 when Ferraro was the first woman nominated for vice-president. In 1984, there were 24 women in Congress. Today there are 127." Geraldine Ferraro, a mother of three-faced an onslaught of sexism and was shamed for being a working mother.

Sexist and racist attacks

Harris was able to use her role as a stepmother of two children to her advantage, painting herself in a softer light by mentioning her stepchildren's nickname for her, "Mamala".

However, she has not escaped sexist and racist attacks.

Trump said she was "disrespectful" and "horrible" to Biden and "extraordinarily nasty" for the way she questioned Brett Kavanaugh during his confirmation hearing for the Supreme Court in 2018.

She also has faced baseless allegations by conservative law professor John Eastman who wrote in Newsweek that she could be ineligible to serve as vice-president because neither of her immigrant parents－her father was born in Jamaica and her mother in India－were US citizens before her birth.

That has been debunked, as Harris was born in Oakland, California, in 1964, and is considered a natural-born US citizen under the Constitution's 14th Amendment.

Newsweek issued an apology.

Dolan believes that despite such challenges, women continue to make strides in politics.

Now 101 women serve in the House of Representatives.

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"We have had an increasing number of women run for office at all levels since then, and have had the first woman candidate for president as well," she said, referring to Hillary Clinton, the Democratic nominee in 2016.