With Senator Kamala Harris as a historic vice-presidential running mate, it's impossible to avoid the topic of gender this election cycle - but are the rules of the race really different for women? Here's how her nomination highlights the issues women in politics have faced for decades - and how things are changing - with analysis from Debbie Walsh, director of the Center for American Women and Politics at Rutgers University. The art of not being angry Women in politics must walk a fine line between assertive and aggressive. Research shows that existing, unconscious gender biases can make women come across as condescending where their male counterparts might be lauded as confident. For minority women, these gender biases are compounded by racial ones too. And in the US, the trope of the "angry black woman" is an old, insidious stereotype. The trope, which emerged in the 19th Century, characterised black women as unfeminine, irrational and sassy. As Ms Walsh explains: "Women are accused of not being strong enough and tough enough to be president or vice-president, but at the same time, how do you portray strength without it being seen as anger?" She feels Ms Harris did a good job toeing the line during the VP debate, but adds that there were some instances were she seemed to hold herself back - although her polite response to the interruptions was "brilliant" and relatable to any woman who has experienced being talked over. Is she fit to lead? Some analysts argue that women have to prove themselves on the campaign trail in ways men do not, even if gender isn't a primary concern for voters. Where people assume competency for men, women must demonstrate it. Economist/YouGov polls in August showed that the sitting vice-president held a narrow lead in favourability compared to Ms Harris. A quarter of Americans polled said they were uncertain how they felt about Ms Harris, and 14% said the same of Mr Pence. After the debate, most voters felt Harris won. But when asked who might be better to take over as president, some polls looked a bit different. YouGov polls found most Americans - 56% - felt Mr Pence was best placed to take on the presidency if Mr Trump cannot serve, while 50% felt the same way about Ms Harris. Among the key independent voter bloc, 53% reported having faith in Mr Pence's abilities, compared to 44% saying the same for Ms Harris. While some survey respondents may simply feel a sitting vice-president is more qualified for the top job than a first-term senator, advocates for women in politics have long argued they have to prove their prowess more than their male counterparts.