Canadian Prime Minister Stephen Harper was in New York Thursday promoting the Keystone XL pipeline, the $5.3 billion project that would move oil from the province of Alberta to the US heartland.

Washington is expected to decide soon on the fate of TransCanada's proposal to build the 1,179-mile (1,897-kilometer) line to the US state of Nebraska, where it would connect with another pipeline to move the oil to refineries in Texas.

Critics warned that a pipeline accident could have a dire impact on the environment and vital groundwater resources -- a fear that Harper, speaking at the Council on Foreign Relations in Manhattan, downplayed.

"The only real environmental issue here is -- do we want to increase the flow of oil from Canada by pipeline? Or by railway, which is far more environmentally challenging in terms of emissions and risks?" asked Harper.

The project "will bring enough oil to reduce America's offshore dependence by 40 percent. This is an enormous benefit for the United States in terms of energy security," he said.

Harper also said the project would create 40,000 jobs in the United States alone.

"These factors, including environmental factors, explain why there is such overwhelming public support for this pipeline in the United States," he claimed.

Seventy percent of Americans and 60 percent of Canadians surveyed by the Canadian polling firm Nik Nanos in April said they had a "positive or somewhat positive view" of the project.

The US State Department in March estimated that the project in its construction phase would create 42,100 jobs over a period lasting one to two years.

But over the longer term, Keystone would add just 35 permanent and 15 temporary jobs, mainly for routine maintenance.

Environmentalists claim the jobs gains are minor compared with the benefits possible with similar investments in wind, solar and other renewable energies.

The State Department is expected to make a final recommendation on the project to President Barack Obama in the coming months.

In Canada, oil companies plan billions of dollars of new investment in the oil sands, and the US rejection of Keystone XL would threaten a key market.

Delays in greenlighting the pipeline will increase construction costs and postpone its in-service date to the second half of 2015, TransCanada said on April 26.