11/17/2014 12:14 EST | Updated 01/17/2015 05:59 EST

Whitby-Oshawa, Yellowhead byelections: What to watch

As voters in two federal ridings head to the ballot box today to fill the seats left vacant by the death of former finance minister Jim Flaherty and the retirement of long-time Conservative MP Rob Merrifield, it is the battle for second place that could turn out to be the biggest story of the night.

While both Ontario's Whitby-Oshawa and Alberta's Yellowhead ridings are expected to stay Tory blue, the Whitby-Oshawa campaign has resulted in a surprisingly close race, according to recent polls.

CBCNews.ca will be updating results in the two byelections after polls close tonight at 9:30 p.m. ET.

The tightening race in Flaherty's former Toronto-area riding may explain why Liberal Leader Justin Trudeau will make an appearance at the election night rally for Liberal candidate Celina Caesar-Chavannes.

According to his office, Trudeau will address the crowd an hour after the polls close, by which point enough numbers should have rolled in to establish a trend, if not necessarily the winner.

Liberals a distant 3rd in 2011 election

Even the most optimistic Liberal strategists aren't predicting an upset win over the Conservatives' candidate, former Whitby mayor Pat Perkins.

But there's a good chance the Liberal Party will at least muster a more impressive showing than it did during the electoral dark days of 2011, when Trevor Bardens came in a distant third to Flaherty, with just 14 per cent of the vote.

That put him well behind New Democrat candidate Trish McAuliffe, who pulled in a more respectable 22 per cent, albeit one still dwarfed by the 58 per cent support garnered by Flaherty during what would turn out to be his swan song on the hustings.

The New Democrats don't appear to be quite so confident in McAuliffe's vote-getting ability this time around — at least, not enough to make sure their leader is within microphone range when the results come in.

Tom Mulcair has instead been dispatched to St. John's, N.L. where he will be at a nomination meeting to confirm the candidacy of incumbent NDP MP Ryan Cleary in Mount Pearl. Cleary will face off against former CTV host turned Liberal star candidate Seamus O'Regan in 2015. 

The governing Conservatives can take comfort in the fact that, unlike recent western byelections in Fort McMurray-Athabasca and Brandon-Souris, Jim Eglinski is expected to cruise to victory in Yellowhead, which elected Merrifield with a whopping 77 per cent share of the vote in 2011.