Is Friday’s convention speech Stephen Harper’s most important as PM?

Stephen Harper has given a lot big speeches in his career as prime minster. After all, you can't hold a minority government for five years (from 2006 to 2011) without meaningful orations.

Tonight's keynote address — at the Conservative Party convention in Calgary — could, however, be the most important speech of his career.

It comes on the heels of an ongoing Senate expense scandal that, despite the Tories' best efforts, isn't going away. A new poll by Nanos Research suggests that "Canadians are more likely to now judge Stephen Harper's performance based on his management of the Senate controversy as opposed to his management of the economy."

And their judgement is soured.

The pollster claims that only 21 per cent of Canadians are satisfied with the prime minister's explanation of his knowledge of the $90,000 cheque written by Nigel Wright to Mike Duffy.

[ Related: Outside audit into wayward Senate expenses cost taxpayers almost $530,000 ]

Conservative delegates gathered in Calgary are also increasingly weary.

While it might be premature to suggest that there is a movement afoot to oust Stephen Harper, there is certainly some aggravation on the convention floor.

"A couple of weeks ago, I would have told you that Harper was good for another 15 years, but now, not so much," Hamilton-area delegate John Mykytyshyn told the Toronto Star's Tim Harper.

"Maybe he takes a walk in the sand six months from now. Things are heading in the wrong direction for us." Liberal MP Joyce Murray who is her party's observer at the convention -- says that she senses a deeply divided membership.

"There were already some very unhappy Conservatives about the kind of deficits and increases in debt, increases in budgets for things like the prime minister's office [and] advertising. Those divisions were already there but the Senate scandal is cracking it open," she told Yahoo Canada News adding that Harper has two choices with his speech on Friday night.

"The prime minister will either acknowledge the divisions in the party and begin to find ways to bring people together or he's going to ignore and pretend it's not happening..in which case it's going to fester more."

[ Related: Senate scandal doesn't distract grassroots as Tories meet ]

Harper's advisers should have two objectives with Friday night's speech: 1) to convince the Canadian public that he has been transparent about the Senate expense scandal and that he has a plan to fix it and 2) To re-energize the base by reminding them of past successes and convincing them that he's the man to lead them into the 2015 election.

Sources have told CBC News that the prime minister will "mention" the Senate scandal but that his focus will be the economy, the EU trade deal and public safety.

Will it be enough to silence his critics inside and outside the party?

The speech gets underway at approximately 8pm (EST).

(Photo courtesy of the Canadian Press)

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