The New Democrats have two high-profile women vying for the nomination: Linda McQuaig, an author and intellectual, and former broadcast journalist and digital expert Jennifer Hollett, who both live in the riding.
Susan Gapka, a singer and activist, is also on the ballot.
The Liberals, meanwhile, will choose between author and journalist Chrystia Freeland, bank executive Diana Burke and Todd Ross, a community organizer.
They're competing for the seat left vacant by former Liberal leader Bob Rae, who stepped down this summer.
The race in Toronto Centre is more important than most, said Peter Loewen, a politics professor at the University of Toronto. If the Opposition NDP is going to win a majority, they would do well to win this type of riding.
But it will be difficult to dislodge the Liberals, who've held the riding for a long time, he added.
"It gives us some bellwether or some reading of the NDP strength versus the Liberal strength," Loewen said.
McQuaig agrees. One of the reasons the race is attracting a lot of attention and well-known candidates is because it comes at such an "interesting, exciting moment in Canadian politics," she said.
The governing Conservatives are in serious trouble in the wake of the Senate expense scandal and seem to be unable to recover, she said. It creates an "incredible dynamic" of which of the two opposition parties will likely emerge as the alternative to the Tories in the next general election.
"So it really does set up a kind of fascinating competition that could, in fact, create momentum for 2015," said McQuaig. "Like whichever party wins ... it would look like the pendulum was swinging towards that party."
But the big-name candidates have also attracted a lot of attention. Loewen noted that the NDP won many seats in Quebec in the 2011 election even though many of their candidates were inexperienced unknowns.
So the byelection will provide a sense of how the party will campaign with a well-known candidate, he said.
"This is really a bit of a showcase of what the next election's going to look like, where Justin Trudeau's going to attract high level, quality candidates, like Chrystia Freeland, and Thomas Mulcair's going to do the same," Loewen said.
Hollett, who was inspired to run after Jack Layton's death, said she's not worried about competing against a star Liberal candidate if she wins the nomination.
"We must not forget that at the doors, voters don't care if you're a journalist, or you went to Harvard, or you wrote a book," said Hollett, who graduated from the world-renown university.
"They don't care. They want to know that you're committed to representing them."
Both say affordable housing and reducing poverty are big issues in the densely populated riding, whose residents live in low-income neighbourhoods as well as some of the most expensive homes in the city.
The NDP are well-suited to replace the Liberals in Toronto-Centre because their policies address those concerns, McQuaig said.
"So I would argue that this is fertile ground for the NDP," she said.
Freeland — whose impressive resume includes degrees at both Harvard and Oxford, editor-at-large of Thomson Reuters and award-winning author — said she's discovered firsthand just how diverse the riding is.
While door-knocking over the past few days, she's met a python expert, a Russian architect and poet and a former diplomat who divides his time between his art gallery and a business in Latin America.
Freeland's top-notch campaign organizers — and her move back to Toronto from New York with her husband and three children — have raised questions about whether the nomination race is as open as Trudeau claimed.
There have been complaints about party rules preventing hundreds of supporters from casting a ballot.
Burke signed up new members only to learn Aug. 27 that they couldn't vote if they hadn't met the Aug. 20 cutoff. She said the retroactive membership cutoff likely affected all the candidates in the nomination race.
Ray Heard, who served as communications director for former prime minister John Turner and supports Burke, urged the party to extend the deadline, saying it would quash concerns that it was set to enhance Freeland's prospects.
Freeland said it's wonderful how many people have rallied around her, but that's really due to her team's efforts — the "building of a new coalition."
"I think that Toronto Centre, in some ways, is going to be the first act of the 2015 general election," she said.
"I think the stakes are very high and it is a very consequential moment. And that, to me, is one of the reasons to do this."
Burke and Ross may not have the same name recognition, but they do have strong community ties from being active in the riding for years.
The bank executive, who has lived in the riding for 25 years, said she has a lot to offer: real world business and technology experience as well as strong local ties.
"As a senior executive at the Royal Bank, I had global responsibilities," Burke said.
"I was negotiating national agreements, multinational contracts and sitting on various international boards. So I have a pretty strong global network."
Ross, a community organizer who works with a number of groups focusing on health care, aboriginal and LGBT issues, and human rights, has been politically active in the local scene for 19 years.
"From my perspective, I think that it's important to be connected to the community, to understand the issues in the community," he said.
"I think that's my advantage and I think that members will be looking at that on Sunday."
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