Tom Mulcair was surrounded by NDP MPs, candidates, and supporters for an appearance at Montreal's Beaver Lake where he announced he hoped a second Orange Wave would sweep the country, much like the 2011 election saw the NDP win 59 seats in Quebec.

He reminded the crowd that Montreal is where he stood by then-NDP-leader Jack Layton eight years ago and declared he would represent the NDP in Outremont in a by-election, and then became the first NDP member of parliament in Quebec.

There are several ridings in the Montreal area that do not have candidates from all parties, and one of them is the newly-altered riding of NDG-Westmount, which is held by Liberal MP Marc Garneau.

Several candidates are hoping to win the NDP nomination, including former Montreal Gazette reporter Sue Montgomery, Projet Montreal city councillor Peter McQueen, and James Hughes, the former head of the Old Brewery Mission.

The party will select a candidate on August 16, and Mulcair said his only regret was that only one person could be chosen.

"It's a reflection of the incredible work done by the team behind me but it's also a reflection of Quebecers' positive reaction to the forward-looking progressive approach of the politics we're putting on the table. I couldn't be prouder to see that many quality people," said Mulcair.

Meanwhile, on a day when the loonie dropped to its lowest value in 11 years, Mulcair used the opportunity to attack Stephen Harper's handling of the national economy.

He also criticized the Conservative leaders negotiation of the Trans-Pacific trade partnership.

"He was never a very good negotiator to begin with, but we are concerned about very important subjects," Mulcair said.

The NDP says it is particularly concerned about Canada's supply management system that relies on marketing boards to control domestic production of eggs, milk, cheese and poultry and high import tariffs to protect against foreign producers.

American negotiators have been pushing to break open that regime in talks on the Trans-Pacific Partnership, a 12-country trade deal that would create the largest trading zone on the planet.

"Supply management is something that has allowed Canadian farming families to hold on to their farms despite the ups and downs," Mulcair said, promising to defend the policy "every step of the way."

In Laval on Monday, Harper said the election campaign would not prevent talks from continuing, or Canada from taking part.

"It is important that Canada remain at the table; we will remain at the table during this election campaign ... and we will make sure that should there be a deal, we will get the best possible deal for this country."

Harper said if the deal is concluded it will "form the fundamental trading network of the entire Asia-Pacific region."

The talks include Canada, the U.S., Mexico and Japan, and would represent some 792 million people and a combined GDP of $28.1 trillion -- about 40 per cent of the global economy.

The Conservatives often accuse the NDP of being against trade deals, but Mulcair said it is crucial to examine the fine print.

"These are things that I have worked on for decades in my career; we are going to be more prudent," he said.

"We are also enthusiastically in favour of a trade deal with our Pacific partners, but what is going to happen? What is going to be on the table with Mr. Harper negotiating that right in the middle of an election campaign?"

Mulcair, who was absent from the campaign trail on Monday, seemed more energetic than he was on Sunday, when Harper triggered the longest and costliest campaign in modern Canadian history.

The NDP leader also opted to take a number of questions from reporters -- something he was criticized for failing to do at the launch of his "Campaign for Change" in Gatineau.

With a file from The Canadian Press