What to expect from Bill Morneau's fall economic update

• LIVE: Watch Bill Morneau's fall economic update here

Rising in the House of Commons on Monday, interim Conservative leader Rona Ambrose ventured a preview of what MPs will hear Tuesday from Finance Minister Bill Morneau, or at least of what she already is prepared to say in response.

"(Tuesday's) economic update is going to unveil even more expensive promises Canadians can't afford," Ambrose said.

Awhile later, Morneau offered a competing setup.

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"What we're going to do tomorrow is talk about our long-term plans to make a real difference for middle-class Canadians for the future of themselves and their families," the minister explained.

The basic parameters of Tuesday's debate are set. but the details will be significant.

How big is the deficit?

The fall economic statement, inauguratedby Paul Martin in 1994, is functionally an update on the fiscal situation a tally of what has changed, or not changed, since the spring budget.

In that regard, the most immediately interesting number will be the budgetary balance for the current fiscal year. In the spring, Morneau forecast a deficit of $29.4 billion. But slower-than-expected growth could increase the shortfall.

Fiscal update: CBCnews.cacoverage

CBCnews.ca will have live coverage of today's fall economic statement beginning after3 p.m. ET, including a livestream of Finance Minister Bill Morneau's speech, stories and highlights.

Then watch a specialPower & Politicswith Rosemary Barton, live on Facebook and livestreaming atcbc.ca/politics.

TD Economics has projected that the deficit will come in at $34 billion, while Scotiabank suggests it will be $30 billion. TD also projects higherdeficits in future years.

Morneau was chided in the spring for booking a "prudence factor" of $6 billion into his projections that cushion could minimize, or even eliminate, any difference now.

What else does Bill Morneau have to offer?

The Conservatives will be happy to note any new amount of debt, but early reports also suggest something more than a simple update of deficit and GDP projections. As the finance minister said, he wants to talk about the long-term plan.

The Liberals came to office promising to stimulate economic growth with new spending, particularly on infrastructure, and they have spent the past year adding to that economic vision with new attention to foreign investment, immigration and innovation.

Morneau comes to today's statement loaded with suggestions from his council of economic advisers, such as calls for anew agency focused on attracting foreign investment and an independent infrastructure bank.

And there remain loose ends to be tied from the spring budget, including a significant second phase of infrastructure spending.

Some of that could factor into Morneau's presentation.

Can the Liberals show economic progress?

As much as the Liberals announced in new spending in their first budget, the Canadian economy remains sluggish a fact Ambrose was happy to remind the Liberals of at question period on Monday.

"Tomorrow, is he going to table a new plan that will actually create jobs?" Ambrose asked, declaring the Liberal approach a failure,"or can we expect the same old, same old, billions of dollars in spending and higher taxes?"

In response, the prime minister said he was looking forward to a plan that would put Canada on a "positive growth trajectory."

On Tuesday, Morneaugets to continue making the case for the Liberal vision, perhaps ask for patience, and explain what he's going to do next.

It will presumably involve more spending, or at least not immediately returning the budget to balance.

But even if the Liberals are thinking long-term,they surely must hope that this is building to something that will show real progress by 2019.