Olivia Chow's bid to return to the Commons and 5 challenges she's facing

Olivia Chow, who was an MP for eight years before resigning to make a failed bid for the Toronto mayoralty, plans to run for the NDP in the new riding of Spadina-Fort York.

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Here are five things which could pose challenges for her as she tries to return to the House of Commons:

1. Adam Vaughan

Vaughan, Chow's chief opponent, is a left-leaning former city councillor who won her old seat in the Commons for the Liberals in a byelection. He is a well-known figure who champions a number of the same issues as Chow, including affordable housing, transit and child care. The similarities between the two could create a fierce battle at the ballot box, political observers say.

2. Riding redistribution

Chow's former riding of Trinity–Spadina disappeared in the last seat redistribution as Elections Canada carved new boundary lines. The new riding of Spadina–Fort York encompasses much of Toronto's downtown core, the waterfront and the harbour islands.

3. Mayoral loss

Chow's much-hyped bid for the mayor's job was a flop and she finished third in the race to replace Rob Ford. She entered the campaign amid high expectations, but never caught Conservative John Tory, the victor, and finished second to him even in areas represented by her old riding. Overall, she couldn't even overtake Ford's outspoken brother, Doug. However, she maintains that running for mayor was an "important thing to do."

4. Returning to the federal political scene

Chow was a well-known figure in the Commons for the better part of a decade. Much of her federal success was part of her personal and political partnership with the late Jack Layton. Her return to federal politics comes as NDP Leader Tom Mulcair emerges from Layton's shadow and puts his own stamp on the party.

5. Political history

As a municipal and federal politician for nearly three decades, Chow has accumulated political baggage which can be used both for and against her. Vaughan recently took aim at Chow in an interview with the Toronto Star, suggesting she is a "serial quitter" with a string of unfinished jobs in her past.