“We should have been doing a better job in this country, in this city,” he said during a breakfast meeting with reporters on Capitol Hill.
Canadian officials, Wall asserted, would have been wise to tell their American counterparts throughout the Keystone XL debate: "Here’s the economic case, here’s the energy security and oh, by the way, we care about the environment and here’s what we’re doing with respect to the environmental piece of this."
Wall's remarks came just a few hours before a Republican legislator in the U.S. House of Representatives detailed new efforts to take the decision on the pipeline out of the Obama administration's hands.
Lee Terry, a Nebraska Republican, is preparing legislation that would do away with the need for a presidential permit for Keystone XL. The permit is currently required because the proposed pipeline crosses an international border.
"If we see further delays as we have in the past; Congress is ready to act," Terry said in a statement.
Two Democrats back Terry's bill, as does Republican Fred Upton, who met with Wall on Wednesday. He's the Republican chairman of the House Energy and Commerce Committee.
Wall is just the latest Canadian politician to head stateside to make the case for the $7.6 billion pipeline, a project that would carry millions of barrels of Alberta oilsands bitumen a week through six U.S. states to Gulf Coast refineries.
Joe Oliver, the natural resources minister, was in Chicago and Houston this week to make a similar pitch, while Alberta Premier Alison Redford was also in D.C. recently. Foreign Affairs Minister John Baird met with Secretary of State John Kerry a month ago.
Wall said officials in both the U.S. and Canada tend to take the bilateral relationship for granted at times, a state of affairs that's caused Keystone XL opposition to become a bigger problem for the Obama administration than necessary.
Canada-U.S. relations need a "little extra tending" on several fronts, Wall said, particularly regarding trade, agriculture and energy issues.
“Like a long-lasting marriage, it’s important to have a date night,” he said.
After his breakfast event, Wall met later in the day with Kerri-Ann Jones, the assistant state secretary who's been leading the State Department's review of the pipeline. An aide to the premier said the discussions with Jones were productive and positive.
On Wednesday, Wall met with mostly Republican lawmakers who already support the pipeline.
But he added he also had a 10-minute "hallway meeting" on Capitol Hill with Ed Markey, a fierce Democratic climate hawk. Wall conceded he didn't change the congressman's mind on Keystone, but assured him that oilsands bitumen would not be destined for foreign markets once it reached the Gulf Coast.
The Conservative premier has not just been cheerleading for Keystone XL during his three days in D.C. He's also been touting his province's $1.4 billion clean-coal project as proof of Canada's intent to cut its greenhouse gas emissions.
Wall says he's also been reminding Americans about Alberta's carbon tax and long-awaited federal government regulations on the oil and gas sector, expected by the summer.
"What the administration needs is some elbow room around the environment," he said at a late-morning panel discussion on North American energy at the Woodrow Wilson Center think tank.
"We need to indicate that we're serious about the environment, because we are, and give the administration the elbow room they need with that remaining flank of opposition to say: 'Here's the record, here's what they're trying to do, and it's meaningful, and it's not inexpensive.'"
He urged pipeline proponents to pivot from focusing primarily on the pipeline's job creation and energy security benefits to heralding Canada's environmental gravitas instead.
Given Saskatchewan currently has no oilsands development, Wall added, he's in a good position to argue objectively in favour of the pipeline to American stakeholders. The province does, however, produce conventional oil that would be transported by Keystone XL.
"We're here principally to make the environmental case," he said.
Pipeline proponents on both sides of the border are increasingly nervous that Obama might want something from Canada in exchange for approving Keystone XL, including a change in Canadian environmental policy.
Wall said such a strategy would "not be helpful," suggested it might violate the North American Free Trade Agreement and noted Canada would never attempt to impose policy stateside in exchange for greenlighting an American project.
Indeed, the premier recently made a high-profile complaint to David Jacobson, the U.S. ambassador to Canada, about speculation the U.S. could go that route.
"There seems to be an inference that it would be easier for the president to approve (Keystone) if there was some kind of quid pro quo change in U.S.-Canadian policy," he said. "We got a response back from the ambassador — and we will take them at their word — that that’s certainly not the case."
The premier added he's confident Keystone will soon be approved, particularly following the U.S. State Department's draft environmental assessment of the pipeline that was dismissive of many of the environmental movement's concerns about it.