Hope is on the way. Jobs are around the corner if we put our 'Million Jobs' plan into action. - Ontario PC leader Tim Hudak

We are going to make sure we clean up this (Liberal) corruption. - Ontario NDP leader Andrea Horwath

They (the NDP and Conservatives) have fallen back into mudslinging and, some very nasty rhetoric. - Ontario Liberal leader Kathleen Wynne

If you've heard those messages already on the campaign trail from the three main party leaders, prepare to hear them all again Tuesday night in the leaders debate.

There are certain realities of all such debates that will be on display when Tim Hudak, Andrea Horwath and Kathleen Wynne take up their podium spots in Studio 40 of the CBC Broadcasting Centre (live on CBC Television, CBC Radio One and CBCnews.ca at 6:30 p.m.).

Debates are not about test-driving new messages or new campaign themes. They're about reinforcing what the leaders have already been campaigning on.

And while all leaders go into these 90-minute encounters hoping to land a "knockout" punch, it rarely happens.

Federally, pundits and political scientists always point to the 1984 debate and the exchange between Liberal leader John Turner and Conservative leader Brian Mulroney.

With Turner out in front, Mulroney needed to make up ground and decided he'd do it in the debate.

He launched into some finger-pointing — debate experts now discourage that — on the issue of patronage appointments created by Pierre Trudeau and carried out by Turner.

Turner responded that he "didn't have a choice." And, on that, Mulroney pounced.

"You had an option, sir, to say no and you chose to say yes."

The line had a devastating impact on Turner for the rest of the debate and into election day.

Mulroney led his party to a huge majority with the election of 211 MPs, reducing the Liberals to just 40.

It was then and is still considered today to be the "knockout punch" of all time in Canadian politics because of its influence on the election's outcome.

Ready for prime time?

In the Ontario context it's hard, if not impossible, to find a comment with the same impact, with the same punch.

That said, to this day provincial Liberals easily remember the 1999 leaders debate that was Dalton McGuinty's first try at the Premier's Office.

ONTARIO ELECTION Debate 1999

Ontario Liberal leader Dalton McGuinty gets fitted with a microphone during a rehearsal prior to the televised Ontario Election Debate in 1999. McGuinty stumbled, but was back in winning form in 2003. (Kevin Frayer/Canadian Press)

At that time, a panel of journalists asked the questions and it fell to me, under the pre-debate agreement between the parties and the broadcast consortium, to ask the Liberal leader a question on "leadership."

The debate was held at a time when the Tories were running what became known as the "Riddler" ad — a photo of McGuinty surrounded by moving question marks.

So my question was to essentially get a response from McGuinty to the ad by asking if he was "ready for prime time?"

Because the panel could not ask follow-up questions, the first one was, as they say, front-loaded: a list of McGuinty's mistakes as leader, including his decision — though he had quickly reversed himself — to hire his brother as a taxpayer-paid adviser.

McGuinty appeared taken aback by the question and his answer was brief, with the now famous words: "Thank you for the question, Robert."

The question caused quite a furor. But, the lack of an answer also sparked a debate within the Liberal party about why McGuinty had not been better prepped.

Some suggested McGuinty's failure to hit the question "out of the park" had cost him the election.

But by 2003 he was better prepared and by 2011, McGuinty was still debating, though the competition had changed to pit him against Tim Hudak and Andrea Horwath.

And while Horwath got high marks for her first-ever provincial debate and some gave her the "win," the reality is that there was no clear winner. After tomorrow night's 90 minutes there may not be one, either.

The rookie

This time around, Kathleen Wynne is the "rookie," the first-timer who comes to the table with political baggage inherited from her predecessor.

And Horwath has served notice — in the so-called northern debate in Thunder Bay — and since that what she calls the Liberal government's "corruption" will be a top-of-mind issue for her.

"Cleaning up the corruption" has become the NDP leader's favourite refrain and the continuation of that and other comments is a clear indication she believes there is traction to be found with it, especially among Liberal voters dispirited by the legacy left by McGuinty.

For Hudak, this debate and its timing, coming as it does so close to election day, is an opportunity, squandered in the 2011 debate, to show voters he is in fact a premier-in-waiting. It's a chance to prove he does in fact have a plan, and that, while it is by his own admission tough medicine, it is necessary to turn the province around.

Hudak is also likely to face some jabs from Horwath and Wynne about his Million Jobs Plan and the numbers that independent economists have said don't add up.

For a man who holds a Masters degree in Economics and often brags about it, the math mistakes are a major embarrassment, though he has defended them and will again Tuesday night.

Wynne too must occupy the high road, to a certain extent, while convincing voters who haven't been paying attention that, while she has apologized for mistakes that have been made, she is not McGuinty.

At the same time, she'll try to convince them that Hudak is Mike Harris, with a plan of cuts that will hurt not help the province.

What comes after

Hanging over this debate — besides the ghosts of McGuinty, Harris and Bob Rae — and perhaps on voters' minds, is what may come from this election.

Kathleen Wynne, Andrea Horwath debate in Thunder Bay

Andrea Horwath, right, sharpened her attacks on Liberal Leader Kathleen Wynne in the May 26 northern leaders debate and in the days since. (Frank Gunn/Canadian Press)

The polls, while they will almost certainly move in some way after the debate, reveal a close race — a virtual tie in most cases between the Conservatives and Liberals, with the NDP solidly third.

The end result may not be very different from what it was before the election: a minority government.

And while the words "corruption" and "math mistakes" dominated the week — the other "c" word, for "coalition," also surfaced.

First, Wynne refused to "rule out" some kind of deal with Horwath to short-circuit Hudak's time in the Premier's Office should he have the most seats on election night.

Then Hudak said "no deals," period, with anyone.

And then, on Saturday, Horwath waded into the hypothetical question and wouldn't rule out propping up Hudak, who has been her sworn enemy — leaving NDP candidates and insiders wondering even more about the direction she was taking the party.

So, there is a lot at stake in Tuesday's debate. 

A solid performance, a bad performance, a mistake — a stumble, an uncertainty, even a hesitation or just a look — may all figure in what people ultimately do on June 12 when they mark their ballot.