And, if they are, to which opposition party — Tom Mulcair's NDP or Justin Trudeau's Liberals — will Canadians turn to replace them?
Four byelections on Monday may provide some answers to those questions.
Byelections are typically considered unique, locally-driven events that have little bearing on what might happen in a general election — as the losers in Monday's contests will doubtless point out.
But these four — in Toronto Centre, Montreal's Bourassa riding and Manitoba's Brandon-Souris and Provencher — seem to be the exception to the rule, as the unprecedented involvement of the three main party leaders attests.
They will provide the first concrete measure of the Senate scandal's impact, the depth of Trudeau's popular appeal and the durability of the NDP's 2011 electoral breakthrough.
"These four byelections are the first act ahead of (the general election in) 2015," Chrystia Freeland, the Liberal contender in Toronto Centre, said in an interview.
"Part of what's being decided is which party will be the alternative to the Conservatives and that's why we're fighting so hard."
Of the four, only the Provencher contest seems a foregone conclusion. Former cabinet minister Vic Toews won the riding with over 70 per cent of the vote in 2011 and it is expected to remain comfortably in the governing party's fold this time.
But in Brandon-Souris, another erstwhile Tory fiefdom, the Conservatives are fending off a surprisingly stiff challenge from the Liberals, who placed a distant, almost non-existent, fourth in 2011.
The riding has been represented by a Conservative for all but four of the last 60 years. In 2011, Merv Tweed won for the Tories with 63.7 per cent of the vote, compared to just 5.4 per cent for the Liberal candidate.
That it's even a contest this time is worrying to Conservatives; defeat would shake a party already reeling from the Senate scandal and potentially spark a challenge to Harper's grip on the party reins.
Prime ministers ordinarily avoid getting involved in byelections but, given the stakes, Harper took the unprecedented step last week of sending a personal letter to Brandon constituents, extolling his government's record and bashing Trudeau.
"Don't let anyone tell you this byelection doesn't matter — there is a lot on the line," Harper wrote, accusing Trudeau of having a "high-tax agenda" and being "soft on crime."
Liberal contender Rolf Dinsdale has benefited from infighting in Tory ranks over what some saw as a fixed nomination process — won by MLA Larry Maguire — and the fact that his father, Walter Dinsdale, represented Brandon as a Progressive Conservative MP for 30 years. But he may be handicapped Monday by the Liberals' lack of a well-oiled organization on the ground.
Still, Trudeau, who has campaigned twice in the riding, doesn't need a victory in Brandon to win. Just a significantly improved showing will be touted as evidence of his appeal and a sign that western Canada need no longer be a Grit wasteland.
But at the same time, he must hang on to Bourassa and Toronto Centre, both longtime Liberal strongholds which have become hotly contested battlefields in the war for opposition supremacy.
"It's an important test for the Liberal party as a whole and it's an important test for our leader," acknowledged Freeland, who is vying to win the seat that was held by former interim Liberal leader Bob Rae.
A loss of either riding would burst the bubble on which Liberals have been floating since Trudeau was chosen as leader last spring. "The Justin effect" has seen the decimated third party rise from the ashes of 2011, back into first place in public opinion polls while the NDP has sunk back to its traditional third-place slot, slightly behind the scandal-plagued Conservatives.
New Democrats have poured all their resources into the two ridings, hoping to at least make a significant dent in the Liberals' margin of victory and, thus, prove they still have momentum under Mulcair, who took over the helm in 2012 after the untimely death of the popular Jack Layton. Snatching either riding from the Liberals would be a coup, touted as a sign that Trudeau is no match for the more experienced Mulcair, who has won praise for his prosecutorial questioning of Harper on the Senate scandal.
"We sense that these 'Liberal strongholds,' these 'Liberal fortresses,' are due for a change," Mulcair said Sunday while campaigning with Linda McQuaig, the NDP's star contender in Toronto Centre.
"We'd love to win it," said McQuaig.
"But we are the underdog. In Toronto Centre, the Liberals have held it for 20 years so I think the stakes are higher for them. Obviously, if they were to lose, I think it would take a little bit of steam out of Justin Trudeau's engine."
The NDP has run aggressive — rival parties say downright nasty — campaigns in both ridings.
In Bourassa, one of the few Quebec ridings to resist the orange wave that swept the province in 2011, New Democrats have put up lawyer and one-time pop singer Stephane Moraille against the Liberals' Emmanuel Dubourg, a former MNA. They've targeted Dubourg, who took a $100,000 severance when he quit provincial politics to jump into the federal arena, as an opportunist.
Mulcair has personally campaigned in the riding six times; Trudeau has been there three times.
In Toronto Centre, Trudeau has joined Freeland on the hustings eight times, Mulcair has campaigned with McQuaig seven times. Both leaders were in the riding, trolling for votes, over the weekend.
McQuaig has relentlessly cast Freeland as a tourist who has lived outside the country for 10 years and has no understanding of the issues facing residents of Toronto Centre. Freeland has hit back, asserting that McQuaig's stance would relegate new Canadians to "the back of the bus."
For Freeland, the byelections are not just over which party should replace the Conservatives. It's about which style of politics — Mulcair's aggressive approach or Trudeau's more sunny, float-above-fray approach — Canadians prefer.
She says she believes Canadians are ready for Trudeau's "positive message" that politics is about public service and doesn't have to be "some kind of nasty gladiator mud-wrestling."
She'll find out Monday night if she's right.
— With files from Will Campbell in Toronto
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