OTTAWA — Conservatives will quietly admit that the insurgents lurking in dusty ditches, desert shrubs and craggy hills of southern Afghanistan represent the most unpredictable threat to their young minority government.

Polls suggest Stephen Harper is solidifying his support while facing a leaderless Liberal opposition, guaranteeing the prime minister smooth sailing in the Commons during his first few months in office.

But it wasn't calm shattered in the Commons that prompted a phone call to 24 Sussex Drive in the early hours Saturday to rouse Harper. His sleep was interrupted by word of four Canadian soldiers killed by a roadside bomb north of Kandahar.

Increasing Canadian casualties in Afghanistan are among the few shoals upon which the Conservatives could founder as Harper charts a course towards a majority mandate.

When several high-ranking Tories were interviewed last week for a story about the relative safety of their government, all zeroed in on the same potential problem area.

"Afghanistan. Absolutely," one said.

The Conservative game plan is simple: deliver on a handful of campaign promises in time for the next election, then pick up about three-dozen or more seats to capture a majority.

Defence Minister Gordon O'Connor said nothing will deter his government from achieving its so-called list of five priorities like reducing the GST and delivering $1,200 cheques to parents.

He made the point at a military briefing on the deaths of four Canadian soldiers.

"I don't think it has any effect on the government's agenda at all," O'Connor said in response to a question.

"The five priorities of the government will go through this spring. We're going through the throne speech now, and we'll have a budget soon, and the budget will also reinforce those five priorities."

As if to underscore that business-as-usual message, the flags continued to flutter high atop Parliament Hill as the government kept up its stoic response to the tragedy.

Every opposition party has offered its support for the Afghan mission, which has so far cost 15 Canadian lives.

But some of Harper's opponents also want a parliamentary vote on the mission when Canada's role comes up for renewal next February.

One prominent military historian said the government must proceed with caution.

Jack Granatstein said Canadians have become increasingly intolerant of military casualties - largely because of the additional media attention paid to them.

"This is a country that had 60,000 dead in the first (world) war and 42,000 in the second. And God knows it didn't like it, but it took it and kept fighting," he said.

"We had more than 100 killed in peacekeeping operations  .. Here we've got 15 casualties (in Afghanistan) and the media response is, 'Are we ready to cut and run yet?' And I think the media response shapes the public response."

A recent poll suggests Canadians are evenly split on the mission. The survey, released earlier this month by Decima Research, said 45 per cent considered the deployment a good idea while 46 per cent viewed it as a bad idea.

But the mission was most unpopular in Quebec - which is a key battleground where Harper hopes to build his majority.

"It is possible that it will do damage to his efforts in Quebec," Granatstein said. "It is striking that the poll numbers dropped after his visit to Afghanistan."

Granatstein said the prime minister would be well-advised to follow the example of his 1950s predecessor Louis St. Laurent.

At the time, the Liberal prime minister signed onto the North Atlantic treaty and took Canada into the Korean war but bucked anti-military sentiment in his home province of Quebec because he was otherwise respected there.

And one Quebec pollster said that's precisely what's happening with Harper.

The prime minister - who is promising the province a stronger voice at international forums while attempting to respond to provincial demands to fix the so-called fiscal imbalance - drew a huge audience during a visit to Montreal last week.

"Quebec has always been more pacifist than other provinces. But (Afghanistan) is not a hot-button issue," said Montreal pollster Jean-Marc Leger.

"Stephen Harper has scored many, many points (here) since the last campaign. This will not change Quebecers' minds. I don't think Quebecers will blame Stephen Harper for what's going on over there."