Politicians will tell you they never look at polls. Except they do. And heading into tonight's leaders' debate on the economy, all three major party leaders are well aware that the top-of-mind issue for voters in this election is the very subject they'll be debating in Calgary.

The timing couldn't be better.

Just this week Canadians learned the federal government ran a $1.9-billion surplus in the last fiscal year. Stephen Harper's Conservatives immediately trumpeted the good news, promoting this new bottom line as part of their campaign theme of strong economic management.

On Wednesday, more economic news. This time not so positive.

The Organization for Economic Co-operation and Development downgraded its outlook for the Canadian economy for both this year and next, saying Canada continues to face "strong headwinds" from the falling price of key commodities like oil.

For New Democrats and Liberals, the OECD's decision is a validation of their argument that it's time for change in Ottawa. The lower outlook became part of their argument that this country's economy is just sputtering along at a pace slower than the rest of the world because of the Conservative government's over-reliance on the promise of the energy sector.

You want a debate on the economy? Let's have it. You want an issue, this is it.

Forget that first debate in August, held in the first few days of this unusually long campaign, Thursday marks the beginning of the real campaign.

Three more debates will follow. Voters will begin to make their choices. Each party has its first, and possibly best chance to break away from the other two in this three-way dead heat.

Connecting with voters

Which brings me back to the polls.

Some people will argue it's no surprise voters list the economy as their priority. A no-brainer even. People always profess to eat their vegetables, too, when asked, even if they don't.

When people identify the economy as the issue they are talking about many things: jobs, taxes, balanced budgets. Or maybe they're mostly concerned about pensions and infrastructure spending.

Liberal Leader Justin Trudeau greats Calgary Mayor Naheed Nenshi at City Hall on Wednesday. The popular mayor met with both Trudeau and NDP Leader Tom Mulcair. (Jonathan Hayward / Canadian Press)

Who knows, maybe their biggest worry is whether Canada fell into a technical recession this year.

So when Harper, Tom Mulcair and Justin Trudeau step out on to the stage in the Palomino Room at Stampede Park, they'll be looking to promote their own agendas across a wide range of topics too.

Each of them will need to make connection between what they're promising, and voters who want to know how any of it will make a difference to them.

It won't be easy. None of the major networks is carrying a live broadcast of this debate, which is sponsored by The Globe and Mail newspaper.

Strategists for all the parties concede that will limit the number of people who will watch, meaning the post-debate news coverage and the views of pundits could be more important than ever in determining how voters react to what the leaders said, and in shaping their opinions of how each one did.

Little wonder the leaders or their designates worked hard on Wednesday to pre-position their opponents as wrong, reckless or both.

New Democrats took the biggest risk, rolling out their financial plan in Ottawa while the leader rehearsed for today's big day back in Calgary.

As promised, the books will be balanced if the NDP wins. The big-ticket promises — like a national child care plan — will be covered by raising corporate taxes from 15 per cent to 17 per cent.

But there are problems. The numbers the party used, for oil prices and growth forecasts, are from the government's 2015 budget. Numbers that are now out of date.

Still, New Democrats say it's more than their opponents have put out.

Pushing the right buttons

"On the important issues, Stephen Harper is hitting the snooze button. Justin Trudeau, on the other hand, is hitting the panic button," said NDP candidate Peggy Nash, who served as the party's industry critic in the last Parliament.

But to use Nash's analogy, the NDP must be hitting the reset button.

This is a party that's determined to convince Canadians that they can be trusted to manage the economy, and to spend on specific priorities such as child care, health and infrastructure, without running a deficit. Or scaring markets.

Party strategists say Mulcair's message Thursday will be that he has the experience (as a former Quebec cabinet minister) to manage the economy, and that the party's plan is fully costed.

Mulcair at a campaign stop in Calgary on Tuesday. Meanwhile, in Ottawa the NDP unveiled its election promises and their costs. (Sean Kilpatrick/Canadian Press)

They also insist the NDP is talking about issues, such as a national $15-a-day child-care plan, more money for health care and for the aerospace and auto sectors, that voters care about.

The Conservatives are just as confident that Canadians see Harper as the best person to continue guiding Canada through what seems like a never-ending sea of troubles foisted on the country from overseas, whether it's Greece's debt, or China's suddenly boom-less demand.

"We're focused on the instability in the global economy," Conservative cabinet minister Jason Kenney intoned from Calgary. "Which is precisely why we need a serious, grown-up national government that is focused on job creation, fiscal discipline and lower taxes."

Experience the difference

Serious. Grown-up. The Conservatives have spent a lot of money already on advertising that aims to portray Justin Trudeau as neither.

Expect Harper to repeat those messages in the debate, arguing Trudeau lacks the experience, and the grasp of economic issues to lead the country now.

For his part, Trudeau certainly sounded serious on Wednesday, when he offered his own scathing assessment of the Conservatives, all the while doing his best to connect with voters who haven't made up their minds yet.

"The Harper Conservatives gave up on helping you a long, long time ago," he told party supporters in Calgary. "They are worried about their own jobs. Not yours."

None of this is really the stuff of debate. It's the grist of a modern campaign, where weaknesses must be highlighted, where votes are sometimes more easily lost than won. And where even the tiniest slip will be replayed over and over again in the days ahead.