The high-profile battle between Liberal Chrystia Freeland and the NDP's Linda McQuaig in Toronto Centre has been getting attention well beyond the riding's boundaries.
Those same two parties are also involved in an intense battle in Bourassa, Liberal Denis Coderre's former riding.
The Opposition leaders certainly seem to sense they have an opportunity to win a previously Conservative-held seat in Manitoba's Brandon-Souris.
In the Manitoba riding of Provencher, candidates are vying to replace former cabinet minister Vic Toews.
Kady O'Malley takes your questions about the four contests.