Canadian prime ministers are more powerful within our system than U.S. presidents are within theirs, but seldom, if ever, has the contrast been greater.
Stephen Harper controls everything in his government, except for the occasional disturbances of a minority House of Commons and a reluctant Senate. He has centralized power even beyond the efforts of his predecessors, insisting that not only every file but also the minutiae of the file be cleared by him.
Barack Obama, by contrast, influences much but controls nothing. Each piece of his astonishingly ambitious agenda is being chewed up and changed by Congress, where his biggest challenges come not from the opposition Republicans, who are predictably against everything he suggests, but from fellow Democrats.
The stimulus package, health care, financial regulation, climate change - you name it and Congress has or had legislative control, even though Canadians might think a president most of them admire is directing traffic.
Mr. Obama is directing traffic, in the sense of a police officer standing at an intersection without lights. Drivers might or might not pay attention to the officer's instructions; and they will go at the speed they choose within the limits of safety. The result isn't chaos, but it isn't orderly, either.
Mr. Obama must appeal over the heads of Congress to the American people, whose voices, he hopes, will influence legislators. Within that broad audience is the Obama army of dedicated supporters who can be activated by the Internet, as well as by his verbal appeals.
The President speaks of ideals, values, visions, challenges and sacrifices, but he can also dissect policy proposals to make them comprehensible, as he tried in his health-care address to Congress last week. He can be teacher and preacher, often in the same speech.
Mr. Harper hates the "vision" thing, seldom speaks of values, never asks Canadians to sacrifice - preferring, instead, to roll out "announcements" of bridges, roads and other infrastructure investments. His speeches are spare, to the point and, usually, very dull. Mr. Obama can lift almost any sentence off a page; Mr. Harper can take his speechwriters' best lines and bury them.
But Mr. Harper can command, whereas Mr. Obama can only cajole, something Canadians might easily misunderstand in this kerfuffle over Buy America.
Mr. Obama can't command Congress to expunge Buy America provisions from its laws, and he certainly won't veto any such law to please Canada. Most of the measures exist at the state and local level, where the President has no sway and where the provisions of the North American free-trade agreement do not apply.
But a president does have considerable sway over his country's foreign and defence policies, and this one has taken on a large array of international challenges in his first nine months, everything from the Israeli-Palestinian quagmire to bilateral relations with Iran, Russia and China, to say nothing of more foreign aid, nuclear non-proliferation, disengagement from Iraq and a new strategy for Afghanistan.
Only on Afghanistan does Canada have anything to offer, because the country has paid the price in blood and money to be heard. As the 2011 date for the end of Canada's military involvement draws nearer, so the country's voice will correspondingly diminish. On everything else, the great issues of international relations, Canada has next to nothing to offer, because the country has largely lost its voice, or lost its appetite even to have a voice, in international affairs.
It's an open question whether the United States would want to hear from Canada anyway, but it's certain that Canada would not be heard when it has so little to say. So the relationship, such as it is, tends to be about bilateral trade issues - mostly raised by Canadians dependent on the U.S. market - that presidents do not find interesting or worth spending any time or political capital to resolve.
Canada could offer ideas on Arctic management, climate change, international institutional reform, oceanic degradation and a range of other world issues, but that would require a world perspective and creative thinking that will not be brought either to the White House or Congress by the visiting Canadian.