A fairly small group of women, urban and Quebec voters could make the difference in Prime Minister Stephen Harper's bid to win the next election. How Harper handles taxes, Afghanistan and the environment may determine how they mark their ballots.

In our latest survey at Decima Research, completed on Jan. 2, about one in every two people reported satisfaction with the overall performance of the Harper government.

That's 13 points more than the final rating we saw for the Paul Martin government, just before they lost office. If everyone satisfied with the new government's performance voted Conservative, Mr. Harper would win a landslide.

Better still for the government, satisfaction rose from 43 per cent in March to 47 per cent in December. However, during the same period, the number of Canadians who said they'd vote Conservative in the next election dropped from the high 30s to the mid 30s.

What explains this different trajectory? And how to account for a 13-point gap between those who are satisfied with Ottawa's performance (47 per cent) and those who tell us they'll vote Conservative (34 per cent)?

First, some of those who are "satisfied"are really saying they aren't as disappointed as they expected to be. Some are saying they're satisfied but feel they'd be more satisfied with a different government. That constitutes faint praise, in other words.

This 13 per cent of voters represents the bottom line for the Conservatives. If Harper wins one in two of them, he could win a majority government. If not, it's a minority or worse. But the Conservatives have been losing rather than making up ground among these voters in the last year.

Here's why.

These voters are more often than not women, and tend to live in cities and suburbs more than rural areas. A fair number are Quebecers who, in the absence of an appealing alternative, default to a Bloc Quebecois vote to promote Quebec's interests with whatever government wins.

For these voters, the next election will turn on which of the Liberal or Conservative parties looks best on a small bundle of "ballot issues." Plausible ballot issues include: the economy, taxes, Canada-US relations, Afghanistan, health care and the environment. And in Quebec, the fiscal imbalance has become the new code for the perpetual issue of whether Quebec is being treated well or fairly enough by Ottawa.

But if success is a function of focus, then it's useful to try to distill the list.

Barring a major change between now and election day, the winner could be the party that looks best on at least two of the following three issues: taxes, the environment and Afghanistan.

These issues are not just nuts and bolts policy questions, but touch on fundamental values of voters and the two big parties. And they are issues that can create distance between the Conservatives and the female, urban and Quebec voters they need.

On these three issues, there's been good news and bad for the Conservatives lately. Ratings on taxes are relatively good - up four points from September.

On international affairs (in recent months a surrogate for Canada's policy in the Middle East and Afghanistan), public satisfaction is low by historical standards, but up four points since September.

On the environment, ratings have dropped by six points to become the single weakest area of federal performance, according to voters. Eighteen per cent credit the government with doing a good job, while 74 per cent say "poor job." Last week's cabinet shuffle may signal to some voters that the government took note of their concerns.

Some analysts argue that foreign and environment policy won't be ballot issues because they rarely have been in the past. This view could turn out to be right.

But for the Conservatives to bet on this view and campaign on other agenda items, such as crime or democratic reform, might prove risky. Times could, in fact, be different.

It's been 50 years since Canada was involved in a conflict as deadly and costly as Afghanistan is turning out to be. And while it's true that environmental concerns wax and wane in relation to swings in the economy, few voters are worried about the economy today, and economic swings are mild. Finally, since Hurricane Katrina, Canadians have become more convinced that the climate is changing and the planet is in trouble. This phenomenon has never been present in any prior election.

And so, female, urban/suburban and Quebec voters will probably turn out to be the "swing voters" who hold the key to whether the Liberals or Conservatives form the next government. They're engaged, want to be impressed, and their votes are up for grabs.

Like other voters, they enjoy lower taxes, but not if that means dismantling key programs: current advantage to the Conservatives.

More than other voters they value environmental action: current advantage to the Liberals.

And more than other voters, they are unsure about the best course of action in Afghanistan: on this issue, no party has a clear advantage at the moment, as news reports from Washington and Kandahar cause swings in public mood.

At the end of the day, the details of these issues may matter less than how they reflect the underlying values of the parties, leaders and voters. These swing voters want peace, but not at any price, want lower taxes, but not at any cost, and want more effort on the environment, with no qualification or prevarication.

Bruce Anderson is president of Decima Research. This commentary was distributed by The Canadian Press.