With Olivia Chow running for the top job in Toronto, her vacant riding of Trinity-Spadina is setting up to be a hotly contested byelection between the New Democrats and Liberals.

The byelection has yet to be called but it will likely be held alongside votes in two Alberta ridings where the Conservatives will be heavily favoured.

All eyes, then, will be on the race in Trinity-Spadina.

The riding was easily won by Chow in 2011 with 55 per cent of the vote, against just 23 per cent for the Liberal candidate Christine Innes (whose return has been denied by the Liberal Party due to the alleged "bullying" tactics of her campaign team).

But the 2011 election was a rather poor one for Liberals, even in their traditional Toronto fortress. Michael Ignatieff failed to win his Etobicoke seat.

The elections held between 1997 and 2008 might be more instructive. Over those five elections, the riding was never won by more than 10 percentage points. Liberals held it from 1993 to 2006, and Chow from 2006 until her resignation.

In 2004, the Liberals barely held on by less than a thousand votes. In Chow's successful 2006 and 2008 election bids, she beat out the Grit candidate by less than six percentage points.

So Trinity-Spadina has the ingredients for a very tight race, considering Liberals are currently leading in Ontario and New Democrats are polling at a lower level of support than they recorded in the 2011 federal election.

The Liberals will not have an easy task overcoming the 31-point deficit they had in 2011 but the byelections in November demonstrated that, given the right circumstances, Liberals under Justin Trudeau can do remarkably well.

However, the byelection held at the time in the neighbouring riding of Toronto Centre suggests Liberals cannot count on wider trends to put them over the top.

Though Chrystia Freeland did improve upon Bob Rae’s 2011 performance in the riding, New Democrat Linda McQuaig also increased her party’s vote share at a time when the NDP was polling just as poorly in the province as they currently are. This suggests that if the NDP can find another candidate with a decent local profile, they should be able to retain much — if not all — of the vote they captured in 2011.

Whether the results will be a taste of the 2015 election is another thing entirely.

The riding boundaries for Trinity-Spadina will be changing significantly for that election, meaning the people who will be voting to replace Chow in 2014 may find themselves in a different riding in 2015.

But the wider implications will still be valid - can the New Democrats resist the reinvigorated Liberals?

Will Trudeau be able to wrestle away a seat that his party would normally be able to win when it is on the upswing? His record in byelections since becoming leader has been very good but anything short of a razor-thin defeat will be seen as a disappointment in Trinity-Spadina.

2014 will be a big year for politicos in Toronto. The race in Trinity-Spadina should provide an exciting appetizer before October's main course.

Éric Grenier taps The Pulse of federal and regional politics for Huffington Post Canada readers every week. Grenier is the author of ThreeHundredEight.com, covering Canadian politics, polls and electoral projections. You can pre-order his eBook, "Tapping into the Pulse", a retrospective of polling in 2013, here.

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