In the Beaches-East York federal riding, Marilyn Churley will be up against Liberal Party of Canada cabinet minister Maria Minna and Green Party of Canada leader Jim Harris. The Conservative Party of Canada has no chance in this riding and will not be taking many votes from the NDP. The main risk is that Harris will draw off uninformed votes, and the Liberals will retain the seat.
Harris is weak in his own party and Churley can win if she goes after him personally for misogyny, imcompetence as a leader, and being (as many in his own party say) a Pointy Haired Boss. There is even a pro-Green anti-Harris campaign called Green Party of Canada because leaders don't matter that Churley can exploit to discredit Harris without necessarily alienating Green supporters (who can easily be convince to vote for Churley as she has good credentials in environmental matters, being a former Ontario Minister of the Environment). Going after the Greens as a party is a bad idea since there is still bad blood from some poor judgement attacks on Greenpeace founder Bob Hunter (who recently died) in a 2001 byelection.
Provincially this riding is held by Michael Prue, another solid consensus-builder. In that same 2001 by-election, Prue bragged on the stand that he had been asked to run by FOUR provincial parties: the Liberals, the Greens, the NDP, and the Province of Toronto Party. So he too has friends in the other parties and can be counted on to help swing votes.