Over the final weekend of the longest election campaign since 1872, the NDP is holding a suite of oversized campaign rallies in key regions, designed to send to voters the message of momentum.

NDP Leader Tom Mulcair and wife, Catherine Pinhas, wave to supporters at a campaign rally in Edmonton on Friday. Canadians go to the polls in the 42nd federal election on Monday. (Ryan Remiorz/Canadian Press)

The events in Vancouver, Toronto and Montreal (following one in Edmonton Friday night) will also serve to rally party activists who will be critical to the party's get-out-the-vote operation — the most expensive and "impressive," in the party's history, according to insiders.

There's a frustrated but relentless optimism in the NDP campaign, rooted in pride in the party's organization and hope in its ground strength among voters in districts key to its success.

The core belief among key organizers is that the national polls don't reflect the truth on the ground. Quebec, insiders say, is still very strong, especially among francophone voters.

In other regions, polling analysis does not account for discrepancies in strength between ridings, one NDP campaigner explained. A seemingly low number reported in Ontario looks much brighter when it's understood there are some ridings in which the NDP is polling 40 per cent and will likely win seats.

[The Conservatives] threw a dead cat on the table. — NDP insider

The party's optimistic view seemed validated in B.C. on Saturday when several thousand people showed up to the rally in Vancouver.

The crowd at the Vancouver Conference Centre was loud and enthusiastic and Mulcair seemed to feed off its support, delivering his case as best he could.

"We have an historic opportunity before us, an opportunity that we must not pass up," Mulcair said. "An opportunity to replace the politics of fear and division with our enduring belief in hope and optimism."

Mulcair also received the blessing of NDP royalty, in an introduction delivered by former leader and party icon Stephen Lewis.

"Mr. Harper has made this election irreversibly personal," Lewis said in a scathing warm-up speech that roused the crowd.

"It's his own views, expressed categorically, that have defamed and defaced the integrity of the prime ministerial office. Tom Mulcair says that Stephen Harper is playing a dangerous game: That game, for crude political advantage, leaves Canadian multiculturalism in tatters."

Early strength

But the NDP's optimism is also rooted in the feeling much of what has happened to its support over the final four weeks of the campaign was beyond the party's control.

"We were running away with it," one insider told CBC News. And then along came the niqab. The source said it's clear to him that Conservative campaigners felt the NDP was running too hot, and needed to have its support struck down.

Success for the Conservatives in many ridings relies on modest support for the NDP, blocking support from the Liberal party.

NDP Leader Tom Mulcair signs autographs during Friday's rally in Edmonton. (Hannah Thibedeau/CBC)

And the NDP's early strength was concerning for Conservatives.

"I don't know if they [the Conservatives] knew it was coming," one source said of the Federal Court of Appeal's ruling on the niqab. But when it arrived, "they ran with it."

"They decided we need to be killed," the NDP insider said, and "they threw a dead cat on the table."

That dead cat struck the NDP hard.

The party found itself on the outside of public opinion in Quebec, where the NDP relies on support from a coalition of Bloc and other largely francophone supporters.

That fact resulted in a 15-point drop in the public opinion polls in two weeks in Quebec, and a five-point drop in Ontario, as well, NDP analysis suggests.

NDP leader Tom Mulcair responds to Conservative newspaper endorsements 0:40

Biased toward Trudeau?

But the real trouble for the NDP was not the niqab (support has bounced back in Quebec), it was the narrative of failure and loss that accompanied the niqab-driven decline.

Some in the NDP camp believe the media has overplayed pictures and footage of Liberal Leader Justin Trudeau, seen here with his son Hadrien on Oct. 12. (Paul Chiasson/Canadian Press)

There's also a belief in some corners of the NDP campaign team that the media was biased toward more alluring pictures and video of the younger Justin Trudeau (and his young and handsome family) over pictures of a grandfatherly Mulcair.

The visual narrative is important in a campaign and it's crucial for a party to tell a strong visual story to engage photographers and videographers.

That's why the party is focusing on holding large rallies on this final weekend of the campaign, to tell the story of public support and strength.

Tom Mulcair and Rachel Notley in Edmonton <a href="https://twitter.com/hashtag/elxn42?src=hash">#elxn42</a> <a href="http://t.co/8zJ6g5h1is">pic.twitter.com/8zJ6g5h1is</a> —@HannahThibedeau

But the party is also working to convert the support it has into seats by using more paid organizers than ever before and focusing a larger share of its campaign budget on supporting that ground game.

By comparison, the NDP believes the Liberal efforts have been focused on the air war — advertisements and the leader's tour — a tactic that has won it broad support in this campaign that may be difficult to harness into seats.

But the NDP are wary the Liberal support could grow even further. If that happens, the Liberal strength would be realized with larger numbers of MPs elected to the House of Commons.

A collapse in Conservative support is largely beneficial to the NDP, say insiders, with better chances for the party to pick up seats in British Columbia, southwestern Ontario and possibly in Saskatchewan — but not in Atlantic Canada, where the Liberals would be the beneficiaries.

Buoyed NDP hopes

The question of how to counter Trudeau's apparent popularity has gone largely unanswered until this week.

NDP leader Tom Mulcair explains why he'd want to meet Parliament soon after the election. 0:51

The story of Dan Gagnier's advice on lobbying from inside the Liberal campaign and his subsequent resignation has buoyed NDP hopes and given the party a hammer with which to smash at Trudeau's so-far clean image.

It was almost with glee Thursday and Friday the party went after Trudeau, comparing the Gagnier story to the worst Liberal excesses during the sponsorship scandal.

Expect that to continue straight through until Monday.

The result, in any event, may not be as positive as the party once hoped.

It's possible, given the math and the way things could shake out, that the election might result in the NDP's second-best result ever.

Not bad, right? But still less than it won in 2011.

Put simply, this weekend still matters.