Dear President Harper

"I would immediately call the president of Mexico, the president of Canada, to try to amend NAFTA, because I think that we can get labour agreements in that agreement right now."

--Barack Obama, speaking at the AFL-CIO presidential candidates debate, Aug. 7.

Senator Obama's little slip of the tongue on Tuesday did not gain much attention in the United States. President of Canada, prime minister of Canada--what's the difference really?

And the fact that the president/prime minister/whatever is a Conservative--and therefore highly unlikely to agree to the labour agreements a President Obama would propose? Details, details.

The Mexican president--his name is Felipe Calderon by the way--is even less likely than Stephen Harper to accede to Obama's hypothetical phone call. "Felipe," President Obama would be saying, "I'd like to revise NAFTA in ways that would price your workers out of U.S. markets. Can I count on your support?"

Oh, well. Presidential debates are not conducted under oath. Candidates pander, distort, evade, promise the impossible.

Still, I think Obama's error does cast revealing light on his candidacy and this election, in three ways:

¥ The mistake draws attention to Obama's general lack of preparedness and experience.

A reference to the "president of Canada" is more than a memory lapse. It is a mistake that reminds us that Obama has never met a Canadian prime minister--indeed, that he has barely ever dealt with U.S.-Canadian issues, notwithstanding that his state of Illinois borders on the Great Lakes and that Canada is Illinois' most important foreign trading partner.

That lacuna in Obama's resume in turn reminds us of all the other things he has never done. Barack Obama has never dealt in any official capacity with any foreign government on any issue, ever. He has never made any important statement on foreign affairs before launching his candidacy for president. He has never borne any kind of responsibility in any area of foreign or security policy. He has never run an organization larger than the office of a U.S. Senator. He has never served in the armed forces of the United States.

If elected president, Obama will arrive in office with less relevant job experience than any president since Warren G. Harding. Maybe that will not matter: Abraham Lincoln did not have much relevant experience either, and he did OK. But maybe it will matter. Nobody will know until it is too late.

¥ The "president of Canada" mistake also casts light on the way that Iraq has crowded out all other international issues for the Democratic field. To listen to Barack Obama's speeches, you would think the world consisted of the United States, the Middle East and Africa. I cannot find anything that suggests that he has ever said anything of substance about the Western hemisphere, except for a glib and unconsidered answer to a YouTube questioner who asked whether he would meet without preconditions with a long list of international thugs and rogues that included Venezuela's authoritarian ruler, Hugo Chavez. (He said he would, an answer that Hillary Clinton immediately and correctly rejected as rendering the U.S. president vulnerable to exploitation "for propaganda purposes.")

Yet these regional issues are likely to loom very large over the next four or eight years. Much of Latin America is threatening to regress back to the bad old days of authoritarian rule and statist economics. The U.S. has benefited hugely from the increase in wealth and stability in this hemisphere since 1990. That benefit now stands in terrible peril, and none of the Democrats shows any signs of having ever considered either the problem or an appropriate American response.

¥ Obama's mistake betrays the awkward truth that Democrats have yet to begin thinking seriously about energy policy.

The Democrats promise (in the words of House Speaker Nancy Pelosi) "an energy policy that will reduce energy prices, reduce our dependence on foreign oil, and reduce pollution." But there can be no such thing as an energy policy for the United States in isolation. Canada is the U.S.'s largest (and most reliable) energy supplier. Mexico has the potential to produce far more energy if only it can unshackle itself from its corrupt and inefficient state monopoly, Pemex.

If a U.S. president is to work effectively with these partners, it would help enormously if he could remember their names--and (even better) show some understanding of their constitutional systems. It's essential to know that Mexicans believe their destructive energy policies to be written into their constitution, and that Canadian energy policy is determined more by the provinces than the federal government.

It's not essential to know that the Canadian federal government is headed by a prime minister rather than a president. But it couldn't hurt.