Voters, either through watching the event, reading the news stories or viewing the video clips, could very well make up their minds based on the performances of Conservative Party Leader Stephen Harper, NDP Leader Tom Mulcair and Liberal Leader Justin Trudeau.
Here are five things to watch for in tonight's debate:
1. Harper 2.0, a more confident Trudeau, a less smiley Mulcair
When it comes to debates, Harper usually strikes a passive tone, a style his handlers likely have said makes him more palatable to the viewing audience.
But Scott Reid, political strategist and former senior adviser to Paul Martin, says Canadians should expect a feistier, sharper and more aggressive Harper this time around.
"He's got to bring a little more spit, he's got to bring a little bit more fire, and he's got to go after the other guys in terms of the deficiencies of their economic programs," Reid told CBC News.
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Trudeau, meanwhile, who by many accounts performed well or at least exceeded expectations in the first debate, will need to project confidence while laying out his economic prescriptions.
"He can't look like he's trying to remember what to say on this fundamental issue to Canadians. He must appear as though it comes out of him without effort," Reid said.
As for Mulcair, whose perma-grin in the first debate inspired chuckles and internet memes, expect a more natural, more relaxed, less smiley performance.
2. The D-word, the R-word, the S-word
They may be the most repeated words of the night — recession, deficit, surplus — although not all candidates will use them with the same frequency. Both Harper and Mulcair greeted the $1.9-billion surplus for 2014-15 as good news. But it's going to be the Conservative candidate who "uses that message at every opportunity" to "demonstrate he is a sound steward of the economy," says Toronto-based political strategist Marcel Wieder.
Mulcair and Trudeau will counter with the R-word; that indeed it's Harper's policies that have led to a recession. And the D-word? It will be thrown around by everyone, as Harper is accused of running six consecutive deficits, while Trudeau defends his plan to run three more in order to fund infrastructure spending.
3. He said, they said
It will be a tale of two economies tonight. Harper will be optimistic, comparing Canada's economy favourably to the rest of the G7, saying that all indicators show things are on the mend and projections are promising. More importantly, he will warn, the biggest threat to stability and growth is from the Liberal and NDP fiscal plans based on more spending and tax hikes (queue the D-word).
As Reid notes, "If you're having difficulty selling your plan you can at least beat up the other plans."
Trudeau and Mulcair will, of course, say the economy is anything but rosy (queue the R-word) and that Harper is out of touch with the thousands (maybe millions) of Canadians in financial strife.
"They are going to have to demonstrate that [Harper's economic figures are] all smoke and mirrors and that they have the plans that will kickstart the economy," Wieder said.
4. It's raining, or pouring, stats
Get ready for an onslaught of figures, statistics and percentages.
As Reid observes, one of the dangers of debates is that they can come off as a "briefing note with hair." Even though it's the best way to dilute a message and lose an audience, politicians can't seem to help themselves when it comes to spouting numbers. There were lots of them bandied around in the first debate. Expect even more tonight.
And while it's a debate, it's also a forum for an extended infomercial. Expect repeated policy plugs — tax credits, spending pledges — to be dropped by all candidates throughout the evening.
5. Think small (business)
Middle income families may be the darlings of most politicians, but small businesses also hold a special place in their political hearts. All three candidates will attempt to boast how their plans will strengthen the economic backbone of the country.
But watch for Harper to use this as an opportunity to lash at Trudeau, who suggested in an interview with CBC News chief correspondent Peter Mansbridge that a "large percentage" of small businesses are simply ways for wealthier Canadians to save on their taxes.
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