Prime Minister Stephen Harper says he is "confident" TransCanada's proposed Keystone XL pipeline will be built, but a major union says the government needs to consider whether the project serves Canadian interests.

The proposed extension would carry oilsands crude south from Alberta to refineries in Texas.

"It's hard for me to imagine that the eventual decision would be not to build that," Harper told Bloomberg Television on Wednesday.

"The economic case is so overwhelming," he said. "The number of jobs that would be created on both sides of the border is simply enormous."

"I'm confident it will be built," he said.

Harper also spoke of how Canada, as an "ultimate friend to the United States," is a reliable energy supplier because it doesn't "use oil or energy projects as strategic resources to achieve... foreign policy or political ends." 

"An integration of Canadian and American energy markets is a great thing, not just economically, but politically and strategically for both countries," the prime minister concluded.

In the Bloomberg interview, Harper was also asked about capital from China being invested to develop the oil sands.

Harper sought to reassure. "We watch these investments very closely to ensure they're economically-oriented investments.  We will not have our resources used to further foreign policy objectives of other countries," he vowed.

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Harper, who will also be appearing on CNBC on Sunday, said the U.S. has an "enormous" need for energy and noted that Canada is "already the largest supplier of energy to the United States."

Labour concerns

The Communications, Energy and Paperworkers Union of Canada has opposed the project since 2009. On Thursday union representatives were on Parliament Hill lobbying 20 opposition MPs to express their concerns about the pipeline. Government MPs did not make themselves available.

"They [Americans] get the jobs and we end up with the environmental mess that's left over," CEP president Dave Coles told a news conference.

"There is an issue of national energy security," he said. "You cannot have an economy that's based just on exporting raw resources."

"Our politicians in Alberta, members of our provincial government, have instead transformed themselves from public officials into little more than salespeople for a pipeline company," said the CEP's Gil McGowan, who is also the president of the Alberta Federation of Labour. "Why on earth are they going south of the border to promote the construction of a pipeline that will clearly create literally tens of thousands of jobs south of the border while creating almost no new jobs here in Canada?"

The union wants Canada to do more to add value by refining its own energy resources instead of exporting raw bitumen. It's calling for the pipeline project to be stopped "before more jobs are lost to the United States."

"The very permit that was granted to build the XL pipeline is now null and void and we think that it has to now go back before the National Energy Board," Coles alleged, adding later that the permit expired in March if there was no construction. The union isn't sure Obama can approve something that doesn't have regulatory approval in a foreign country.

"My hope would be that the prime minister would do the right thing this time and actually bring it into the House of Commons and let the light shine on this debate," Coles told reporters.

Pressed later during question period, Natural Resources Minister Joe Oliver pointed out that the oil sands are responsible for over 140,000 jobs across Canada. "The number is expected to grow to almost half a million jobs, and that's how many the opposition says no to when they bash Canada abroad," Oliver said.

Ottawa protest to come

A large anti-pipeline demonstration is planned for Parliament Hill next Monday, September 26. CEP will participate in that rally.

Environmental activists opposed to the project have staged a string of protests outside the White House in a bid to stop the project.  Environmentalists have also expressed concern about a possible oil spill, pointing to the pipeline's route through sensitive lands in the U.S. Midwest.

In late August, U.S. State Department officials said there was no indication the pipeline would pose a significant risk to the states it crosses.

The State Department — which is charged with determining whether the application is in the U.S. national interest — is expected to release its decision by the end of the year.

With files from The Canadian Press