SINCE leading his Liberal Party back to power in Canada last October, Justin Trudeau has been profiled in such glossy magazines as Vanity Fair and Vogue; Hello’s photo spread featured his wife and children. On March 10th he will sit down with Barack Obama at a state dinner in the White House, the first for a Canadian leader in 19 years. “I can’t think of a Canadian politician who has attracted as much attention in the United States,” says Laura Dawson of the Canada Institute at the Woodrow Wilson Centre in Washington.

Mr Trudeau owes his celebrity to more than glamour. He succeeds Stephen Harper, a prickly Conservative, who in ten years as prime minister conducted an ideologically charged foreign policy at odds with Canada’s multilateralist traditions. His relationship with the United States, by far Canada’s most important, was tense. Mr Trudeau replaces a scowl with a smile. He personally greeted some of the 25,000 Syrian refugees Canada agreed to admit. Such gestures have helped bring back to life the Trudeaumania inspired by the prime minister’s father, Pierre Trudeau, a dashing Canadian leader of the 1960s, 70s and 80s. “But how,” Ms Dawson wonders, “do we translate celebrity into influence?”

Mr Trudeau’s answer: by returning to Canada’s diplomatic traditions. It is the world’s tenth-largest economy; as a military power, it counts for less. It has historically sought to increase its modest clout by working through international bodies such as the UN and the Commonwealth. Mr Harper spurned them as talking shops for despotic regimes. He refused to support a global accord on climate change (or introduce a credible policy in Canada).

Co-operation is back in, says Stéphane Dion, the new foreign minister. His “mandate letter” from Mr Trudeau directs him to resume working through the UN. Mr Trudeau signed the global climate agreement reached in Paris in December. He was due to meet Canada’s 13 provincial and territorial leaders on March 3rd to talk about a national climate strategy and may announce a climate initiative with Mr Obama.

The prime minister intends to re-establish diplomatic relations with Iran and to revive Canada’s relationship with Mexico, its partner, along with the United States, in the North American Free-Trade Agreement. He promised to lift visa restrictions on Mexicans, imposed in 2009 to stem an influx of asylum-seekers and an irritant ever since.

He is not rolling back all Mr Harper’s policies. Canada is likely to ratify the free-trade agreement with the European Union, which Mr Harper negotiated. It may also join the Trans-Pacific Partnership among a dozen Asian and American countries. “We should not change everything,” said Mr Dion in a recent speech.

If Mr Trudeau just gets along with Mr Obama, that will be a significant change. The two sporty leaders have engaged in pre-prandial raillery about which country’s ice-hockey teams are better. Mr Obama has taken with equanimity Mr Trudeau’s decision to withdraw Canada’s six fighter planes from the United States-led fight against Islamic State; Canada is increasing humanitarian aid and the number of troops advising Iraqi Kurds instead. The Keystone XL pipeline to carry crude from Alberta to the southern United States, greatly desired by Mr Harper but vetoed by Mr Obama, is unlikely to figure much in the dinner-table conversation.

That leaves trade and tax. The United States is the market for three-quarters of Canada’s goods exports and the source of two-thirds of its imports, but commerce could flow more freely than it does. The “beyond the border” agenda is supposed to accomplish that but has hit a snag: a disagreement over what law will apply to United States officials stationed in Canada to pre-clear goods for import. A row over Canadian softwood lumber, which the United States says is subsidised, could get worse. Canada objects to a United States law that obliges its banks to hand over information about accounts held by expatriates (see article).

But the main threat to Canadian-American relations will not come from anything the two leaders feasting in the White House might do. It comes from the loud-mouthed property mogul who aspires to be the building’s next occupant.