By John McCrank and Jonathan Spicer
NEW YORK (Reuters) - The logic behind the Keystone XL pipeline is "simply overwhelming," Canadian Prime Minister Stephen Harper said on Thursday, adding that U.S. President Barack Obama had assured him his decision on the project would be based on facts.
Addressing a business audience in New York, Harper said he was optimistic that Obama would approve TransCanada Corp's pipeline from Canada to the United States.
"I remain an optimist that notwithstanding politics, that when something's so clearly in everybody's interests - including our interests as Canadians and the national interest of the United States - I'm of the view that it has to be approved," he said.
Referring to a broad pro-Keystone coalition grouping governments along the route, business and much of the labor movement that supports it, he said, "My view is that you don't take no for an answer."
Despite economic support, Obama has faced intense lobbying from environmental groups that argue the oil pipeline, which would run from Canada through the United States to the Gulf of Mexico, will aggravate climate change.
Harper said the project would create 40,000 jobs in the United States, a number parallel to the U.S. State Department's analysis in March that it would support 42,100 jobs.
The State report also said the project would not likely change the rate at which the Alberta oil sands are developed, another of the environmentalists' concerns.
"The State Department report on this is clear. The president has always assured me that he will make a decision that he believes is in the best interests of the United States based on the facts. And I think the facts are clear," he said.
"The logic behind this project is simply overwhelming."
Harper sent Obama a letter this month in his drive to win Keystone approval, government sources say, proposing harmonization of the two countries' regulations in the oil and gas sector.
The White House on Thursday beat back an attempt by Republicans to link a measure to approve Keystone to a bill to raise the debt limit, saying it would reject legislation that includes that provision.
(This story has been refiled to add word "letter" in second-last paragraph)
(Writing by Randall Palmer and David Ljunggren; Editing by)