The political leaders have sent a joint letter to Obama that says the pipeline is crucial for energy security and the future economic prosperity of both countries. They also say it will create thousands of jobs on both sides of the border.
"There are a number of important elements to Keystone that are important for Saskatchewan, that are important for Canada and ... important for the United States," Wall said Thursday at the legislature.
"And so we wanted to work together with our friends in the United States, with these governors, and put forward what we think is a very compelling case for the U.S. administration to approve Keystone."
The TransCanada (TSX:TRP) line would carry bitumen from the Alberta oilsands to U.S. refineries in the Gulf of Mexico.
Wall, who has repeatedly called for Keystone's approval, admitted his role as a provincial premier isn't likely to hold much sway with Obama.
"But that's why we tried to partner with governors who would have a lot more influence ... in the capital," he said.
"I also think where we can have a positive impact in Saskatchewan is to get some information out. As I chatted with the governors on this particular letter, I pointed out to them I think we've all fallen down in not talking about the fact that one in seven barrels of the oil in the pipeline is actually American oil."
Wall said the pipeline could also be used to carry oil from the Bakken formation, which is under parts of Montana, North Dakota and Saskatchewan.
Alberta Premier Alison Redford was not among the politicians who signed the letter, but Wall said he doesn't see a problem with that. Redford has been working hard on the file and Saskatchewan wanted to do its part, he said.
"I think this is helpful where you have the province of Saskatchewan, with a real stake in the project, also taking a bit of a lead and so we're happy to do that," he said.
A spokesman for Redford said in an email to The Canadian Press that he did not believe she had been specifically asked to sign the letter.
"That said, Premier Redford welcomes every bit of support for Alberta's efforts to open new markets, and as today's letter speaks to, it's in all of Canada's interests for Alberta to succeed in opening new markets for our oil," said Stefan Baranski, director of communications for the premier's office.
TransCanada said in a statement that it appreciates the support from Wall and the governors.
"As Premier Wall and others recognize, Keystone XL will provide a safe, secure supply of Canadian and U.S. crude oil to U.S. Gulf Coast refineries, forcing out higher-priced, unstable conflict oil from regimes that do not share North American values."
Obama rejected the pipeline last year after environmental groups put enormous pressure on his government. But the government invited TransCanada to file a new application with an altered route that would skirt an ecologically sensitive area in Nebraska.
TransCanada has done that. Nebraska's environmental regulator said in an evaluation of the line's revised route that it would have "minimal" ecological effects in the state. The state's governor is reviewing the report and is expected to make a decision in the next couple of weeks.
The U.S. State Department, which has jurisdiction because the pipeline crosses an international border, is to make a recommendation to Obama after that.
There has been speculation a final decision could come soon.
But former Alberta premier Ed Stelmach, speaking at an economic conference in Edmonton, said he doesn't agree with predictions that Keystone could be approved in the next three months.
"We're lucky if we get any approval — if we do get an approval — by the end of 2013," he said. "And if we get it sooner, so be it, that's still two years of construction time."
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