Prime Minister Stephen Harper says Canada is still working on a security border agreement with the United States.

But even though there's no perimeter security agreement yet, critics fear Canada's already giving too much away in the face of new threats to free trade between the two countries.

A final deal between the countries is not imminent. Sources told CBC News that even organizing an event to announce an action plan towards a perimeter security deal is proving difficult during the American pre-election season, when U.S. President Barack Obama's priorities lie elsewhere.

And even as talks continue to make it easier for people and goods to cross the border, new evidence of American protectionist instincts — most recently in a new "Buy American" clause Obama's America Jobs Act.

But it was also in a threat by the U.S. Federal Maritime Commission to add a tariff to cargo shipped into Canadian ports and then across the U.S. border — call into question whether Americans are really serious about having a more open border with Canada.

"You still have this underlying protectionism in the United States which really hits us and really discriminates against us," said Liberal Interim Leader Bob Rae on Wednesday. "I think the government should hold back on the perimeter deal until we get some real assurances on these other acts of discrimination against Canada and against the Canadian economy."

Rae warned that Canada shouldn't be too eager to make a deal under the circumstances, saying "if you give in now, you've got nothing to play with when they come back at us with all of these other measures."

Government 'pleased with progress'

Eventually, an agreement of some kind is expected to implement new common customs requirements for border crossings.

But CBC News has learned that the most contentious issues, such as immigration, refugee standards and the harmonization of some security measures, have been stripped out of the agreement.

In question period Wednesday, the NDP expressed skepticism that talks are really going Canada's way.

"This government has a proven track record of being very bad negotiators [with the United States]," said Brian Masse, the critic for the U.S.-Canada border. "Why should Canadians trust them?"

Public Safety Minister Vic Toews said Wednesday that it takes time to work through "36 separate headings that are all very complicated," but that the government is pleased with the progress so far.

"We're on track. Everything is according to schedule," Toews said, contradicting reports that a deal had been delayed from the fall target for an announced action plan. "When you build a house you don't build it overnight."

Toews also denied that the recent re-emergence of the "Buy American" issue was a problem. "We believe that the benefit to Canadians will be quite substantial in terms of trade."

Immigration Minister Jason Kenney said that the nagging trade threats shouldn't delay the perimeter plan.

"I think we're capable of walking and chewing gum at the same time," Kenney said. "We can continue the initiative for the security perimeter while vigorously raising our concerns about protectionist policies.

"There are always going to be some kinds of irritants in the bilateral relationship," Kenney added.

The immigration minister pledged that the end result for Canadians would be "easier and faster travel" across the border.

Liberal international trade critic Wayne Easter expressed concern about the secrecy surrounding the talks so far, suggesting the government wants Canadians to "buy a pig in a poke."

"Canadians need to know how much is our personal privacy going to be affected by this perimeter security proposal, and is there going to be any impact on Canadian sovereignty," Easter said.

With files from The Canadian Press