Before launching her bid for Conservative leadership, Lisa Raitt had to decide: Would her husband survive without her?

Bruce Wood, Ms. Raitt's long-time partner, was diagnosed in June with early onset Alzheimer's. Only in his mid-50s, it was devastating news for the couple, who decided to marry in September after seven years living together.

"I cried for four weeks. And then you stand up, brush yourself off and say 'Okay, well let's get on with this. What are we going to do? How am I going to help him? What am I going to do in my life?'" Ms. Raitt recently said over lunch in the parliamentary dining room.

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"It's terrible. It happened. But I've got to deal with it. So we're going to deal with it."

The diagnosis didn't just impact Ms. Raitt, a mother of two teenage boys, on a personal level. It seeped into her professional life, too, as the former cabinet minister who held three portfolios in the Stephen Harper government weighed her political future.

As her leadership decision became more serious, Ms. Raitt spoke with Mr. Wood's doctors about where he stood in the hazy world of Alzheimer's. Could she leave him alone? (Yes.) Could he still drive? (Yes.) Could he still fix things in his workshop, still cook her food she wasn't too fond of? (Yes, and unfortunately, yes.)

"I became very comfortable with the fact that this was something I could do," said Ms. Raitt, who officially joined the leadership race in November. "And here I am."

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Ms. Raitt's situation makes her unique among the 14 Conservative hopefuls vying to win the leadership on May 27. One of only two women in the race, she is balancing both motherhood and an ailing spouse, facing an uncertain personal future as she fights for the helm of a party that is also trying to find its way.

She said she decided to share her husband's struggle to maintain a degree of normalcy in their lives. Not to shy away from the disease, but to live openly.

"There's no shame," she said.

It's a lesson she learned early in life. Ms. Raitt didn't know until she was in her early teens that her parents were actually her grandparents. Her sister, a young unmarried woman who almost gave her daughter up for adoption, was actually her mother.

"I just decided that was not a way to live a life. So if somebody asks me a question, then I'm up front. And I do talk about it. Because those things I can't control," she said.

With five months left in the race, Ms. Raitt hasn't been as visible as some of the front-runners. Kellie Leitch, Maxime Bernier, Andrew Scheer, Michael Chong and potential candidate Kevin O'Leary have thus far dominated the discourse, based on their policy planks, fundraising numbers, caucus support or, in Mr. O'Leary's case, sheer name recognition.

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Ms. Raitt also lacks French, which she is working to improve, as shown by her casual conversations with a waiter.

But she swears she only has one target in the race: Prime Minister Justin Trudeau.

"I looked at the candidates in the field, and I thought, well, who can beat him? And I realized that I'm the best one to beat him," she said.

Ms. Raitt grew up in Sydney, Cape Breton, but has represented the Toronto-area riding of Milton since 2008. The former finance critic with extensive management experience in the private sector said her decision to join the race was spurred by big-spending decisions being made by the Liberal government.

She repeatedly references her modest upbringing and blue-collar roots as a way of contrasting with the privileged life of Mr. Trudeau.

"Let me tell you what my family says. 'Lisa, you weren't born with the silver spoon. You were born with the red Dairy Queen Blizzard spoon.' Because I worked at the Dairy Queen," she said.

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The former CEO of the Toronto Port Authority, who wrote the port's first maternity-leave policy, said her leadership style is collaborative, but confident. Most important, she said, is to treat everyone with respect.

"We should never look with fear to anybody else," she said, while steering clear of referencing Ms. Leitch, who has proposed Canadian values screening for immigrants. "My sights aren't on Kellie, who's a friend," Ms. Raitt added.

A practising Catholic, Ms. Raitt said as leader she would not reopen the abortion debate, but would let private members have their say.

"I'm being clear right from the beginning, I will not introduce legislation even through the back door," she said.

As she finds her footing in the leadership contest, Ms. Raitt said she has learned to focus on what she can control in life. She eats better, drinks lots of water and gets plenty of sleep – "it cuts into my partying," she laughs – which also helps Mr. Wood maintain his health.

"I can't change the fact Bruce has Alzheimer's, but I can shape what the future looks like," she said. "And I'm going to do that."