Voters are headed to the polls for federal byelections in Manitoba and Quebec today — and the results of these two local contests could have national implications.

One seat, the Winnipeg-area riding of Elmwood-Transcona, has been held by the NDP for most of the last four decades, while the other, Montreal's LaSalle-Emard-Verdun, has been solidly Liberal.

A victory by any other party in either of these elections would be a major upset and could lead to some soul-searching for the Liberal Party and…