Canada's first - and only - female prime minister says some of the criticism levelled at Hillary Clinton is simply sexism, but she's hopeful a Clinton victory will set the stage for future women leaders.

Kim Campbell was prime minister for six months in 1993, after winning the Progressive Conservative leadership following Brian Mulroney's resignation. She went on to be Canada's consul general in Los Angeles and taught a course on gender and power at Harvard's Kennedy School.

Campbell, who was also Canada's first female justice minister and the first female defence minister of a NATO country, says atypical leaders like Barack Obama or Hillary Clinton – those who are non-white and non-male – can make people uncomfortable.

"You know, you don't look or sound like the people that they're used to [being in charge]. So they try and find ways of validating that discomfort," Campbell said in an interview with Evan Solomon, host of CTV's Question Period.

"The person who is trying to set a new standard or be a new type of leader often finds that you don't get the benefit of the doubt, that people are looking for ways to reconcile their visceral discomfort with the fact that they don't consciously think that they could be conceivably be biased," Campbell said.

Campbell says she started to look at the field of research called implicit attitudes when she first left office. She sees it manifesting in certain criticism of Clinton.

"There's just an unwillingness even to accept the fact that she's run an incredible campaign," Campbell said.

To the argument that Clinton is only winning because Trump is a terrible candidate, Campbell says, "No. She actually has been a remarkably effective politician fighting this candidate that none of the men in the Republican Party could get a handle on."

In her own case, Campbell says, the sexism was difficult to parse. "People are entitled not to like you because of what you stand for," she said.

But she hopes, if Clinton wins, it will affect people's perception of what a leader looks like.

"The only answer is to be there and do the job. As she occupies that job, people will get more used to the idea of a woman doing it. You change the landscape that tells you how the world works. So there are a few human sacrifices early on while you're tackling those preconceptions. But the only way to do that is to be there."

Trudeau wise not to criticize Trump

Canadian politicians have mostly be careful to avoid criticizing Trump, no matter what he says. Prime Minister Justin Trudeau generally avoids directly answering questions about Trump's policies and instead talks about his own values.

Campbell says that's wise.

"If he gets elected, they somehow have to deal with him," she said.

"He's unbelievably vindictive.... So given the nature of the Canadian-American relationship, I think it's probably just as well for [Trudeau] to keep his powder dry."

The former PC leader says she hates to see the destruction of the Republican Party, which has split over Trump's candidacy and his appealing to the fringes of the political right.

"You have people in the Republican Party that are trying to convince themselves that it's okay. They cannot accept the fact that they've nominated this terrible person," Campbell said.

"If America doesn't have two dynamic parties offering identifiable choices to the voters, of a kind that's consistent with democratic values, then it's a great loss."