The NDP is stepping up its offensive against the Trans-Pacific Partnership with a new attack ad designed to drum up support for the party as the October 19 Election Day draws nearer.

The ad, which started running on Sunday, criticizes the 12-nation trade deal for including countries where the "wages are low" and "environmental laws are weak."

It also points to Doctors Without Borders' disapproval of the agreement with an argument it will "drive up" the price of prescription drugs, and claims that it will also "drive down wages."

The ad also takes aim at Conservative Leader Stephen Harper for negotiating the deal "in secret" and Liberal Leader Justin Trudeau for not being "clear" in his position.

NDP Leader Tom Mulcair has emphasized that his party does not support the trade deal in its current form.

At a campaign rally on Vancouver Island on Sunday, Mulcair said the NDP "will not be bound by Harper's secret deals" and will "fight for a better deal for Canadians."

"Harper won't release the full details of it, and if he's so proud of it, why won't he show it to Canadians?" said Mulcair.

The full text of the agreement has yet to be released, but Mulcair says he's seen enough in his briefings to predict it will cause drug costs to go up, wages to go down, jobs to be lost and it could be "devastating for the environment."

In an appearance on CTV's Question Period Sunday, also expressed concern about the implications for Canada's auto and dairy sectors, and commended U.S. Democratic presidential hopeful, Hillary Clinton, for opposing the agreement.

"We would never put that deal before Parliament. We would try to get a better deal, the same way Hillary Clinton says that she doesn't like the deal that's been negotiated for American working families, I don't like the deal that's been negotiated," Mulcair said.

"And you can understand if Hillary Clinton finds it's a bad deal for American families, you can imagine how bad it is for Canadian working families, because we got a worse deal than the Americans did on auto," he added.

The NDP has seen their support plummet in the past several weeks, dropping to third place behind the Conservatives and the Liberals, according to the latest polling.

However, the TPP could act as a wedge issue, especially in B.C. where the trade deal could have the most perceptible effects. Countless goods departing to and incoming from newly opened markets in the Pacific Rim will pass through the province's ports.

B.C.'s forest and technology sectors could also be affected by the deal, which Mulcair highlighted in his rally speech in Vancouver on Sunday.

With files from The Canadian Press