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The good news for Stephen Harper is that the electoral map continues to tilt in his favour, thanks to a political landscape that could see the Liberals take more votes but win fewer seats than the Conservatives in the next election.
The bad news is, that landscape could soon change.
If voters place jobs and growth at the top of their political agenda, the Conservatives are still likely to win in 2015.
But if the scandal over Senate expenses becomes their top concern, the imbroglio could bring down the Prime Minister.
"If he's not careful, the Senate scandal could be for Stephen Harper what the Adscam scandal was for Paul Martin," warns Darrell Bricker, head of the polling firm Ipsos Reid Public Affairs.
"Incumbent governments are expected to be in charge. If something goes off the rails when you're in charge, you can't escape it."
Although polls have been few and far between recently, "for the Conservatives, things have been pretty stable," at around 30-per-cent support since last winter, observes Eric Grenier, whose threehundredeight.com assesses and weights political polling data.
After a spike of popularity in the spring, when he became leader, Justin Trudeau's numbers have drifted down; the Liberals now hover in the low-to-mid thirties, while the NDP under Thomas Mulcair are in the low-to-mid twenties.
That's important: The NDP's old ceiling of 20-per-cent support is now their floor, which is bad for the Liberals and good for the Conservatives.
This means that, first the first time since who-knows-when, the Conservative vote is more efficient than the Liberal vote, Mr. Grenier and Mr. Bricker believe.
The Liberals now completely dominate Atlantic Canada because of Conservative moves to tighten employment insurance.
The problem is, "that's not much of a base," says Mr. Bricker. Atlantic Canada will have only nine per cent of the 338 seats in the House of Commons in the next election.
(For the record, Mr. Bricker and I collaborated on a book on Canadian politics published earlier this year.)
The Conservatives dominate in the prairie provinces, rural Ontario and the interior of British Columbia. The Tory base is more than twice as large as the Liberal base, in terms of seats.
The Liberals hope to make major gains in Quebec, where NDP support is flagging. But much of the NDP vote appears to be moving to a resurgent Bloc Québécois, although "I think that's definitely parking," says Mr. Grenier.
Regardless, in the next election Quebec will likely be an NDP/Liberal/Bloc fight. But again, the Liberal vote is inefficient, concentrating heavily in the West Island of Montreal.
In Greater Toronto and Greater Vancouver, where the election will probably be decided, the NDP threatens to siphon Liberal support. And suburban voters place a heavy emphasis on economic issues, where the Conservatives continue to score well.
Put it all together, and the Conservative advantage on the economy, a strong NDP, and Liberal dominance in areas with relatively few seats could create a situation in which the Liberals lose the next election even if they win the popular vote.
"Unless the Liberals have a four-to-five-point lead, they are not assured of winning the most seats," Mr. Grenier believes.
All of that, however, fails to take into account the Senate scandal.
Pierre Trudeau's obsession with constitutional reform; Brian Mulroney's obsession over Meech Lake and Charlottetown; the sponsorship scandal – all were fatal to the governments of the day.
If the spending scandal continues to grow, it could force voters' minds off the economy and onto the question of Senate reform. No matter how he handles that question, Mr. Harper will be punished by the voters for it, Mr. Bricker believes, "because there's really nobody else to punish."
Even if the Tory base stays loyal, the Senate scandal has led to "a noticeable increase in the percentage of voters who are now inaccessible to them," pollster Nik Nanos, of Nanos Research, believes.
These are the voters who might be persuaded to vote Conservative, or might not.
"The challenge for the Conservatives is that they need those voters to be accessible in order to form a majority government," said Mr. Nanos. " As more voters take the Conservatives off the political menu, it becomes more difficult for the Tories to win a majority."
The Senate, in other words, is a political wild card. Who holds that card and how it gets played could determine who is prime minister two years from now.
John Ibbitson is the chief political writer in Ottawa.