WASHINGTON -- Two historic figures in American politics spoke about the Canada-U.S. softwood lumber dispute this week -- one sympathetic to the northern neighbour, and the other less so.

The good cop: John McCain.

Bad cop: Jimmy Carter.

The ex-presidential nominee and ex-president offered contrasting views this week on the Trump administration's decision to slap duties up to 24 per cent on Canadian lumber and initiate the latest round in a recurring trade feud.

McCain lamented that this was a poor way for President Donald Trump to start relations with a neighbour.

"Couldn't we have tried to sit down and negotiate that issue? Rather than send the message early in the administration that we're going to retaliate?" the Arizona senator said during a conference at the U.S. State Department on Tuesday.

"I'm not sure that's how we want to treat our relationship with Canada."

That was music to the ears of Canada's trade minister.

Francois-Philippe Champagne met with McCain after giving a speech at the same conference. He said Canada is weighing what he calls "options" -- others call them "threats" -- to hit U.S. coal exports, and Oregon industries, in retaliation for lumber duties.

He said Canada is looking to diversify its trade, so it's less reliant on one partner, and that it might become what Champagne described as an international trade bridge -- linking Europe and Asia.

As Canada pushes to revive the Trans-Pacific Partnership, open trade talks with China, and enter a new deal with Europe, the U.S. is withdrawing from TPP, seeking to reduce imports, and favours bilateral trade deals over big multilateral ones.

"Canada is working hard to realize an ambitious agenda of trade diversification," Champagne said.

"This includes pursuing new markets for softwood lumber, given the recent U.S. duties. We believe these duties to be unfair and unwarranted and we are taking steps to defend our industry, as you would do."

America's 39th president would beg to differ.

Carter penned an op-ed in the Washington Post titled: "Trump is right. Canada's lumber trade practices are unfair." Carter conceded that he has a personal stake in this, as lumber sales are a major source of income for his own family.

"We have suffered financially for many years from an unfair advantage enjoyed by our major competitor in this vital market, (Canada)," he wrote.

"Canada enjoys an inherent advantage in that the vast majority of its standing timber is owned by provincial governments, which are free to dump their timber at practically no cost in order to stimulate their forest industry... Largely because of Canada's unfair trade, the prices we receive today are the same as when I was in office over 35 years ago, although expenses ... are much greater."

He said that the U.S. could supply all of its own lumber needs with moderate adjustments in management practices. It could supply 84 per cent of those needs, he said, if only Canada changed its logging practices.

But now, he noted, the U.S. supplies less than 70 per cent of its own lumber and imports more than 30 per cent from Canada.

The Canadian government and its allies in the U.S. home-builders' lobby offer a counter-argument: that any move to drive up the cost of Canadian lumber has consequences, with more expensive home construction, and a hit to home buyers.