Just back from a whirlwind international tour taking selfies with adoring fans, dining with Queen Elizabeth II and vowing strong action on climate change, Canada's new prime minister now faces big challenges at home, including a sluggish economy.
Justin Trudeau was cheered at summits in Paris, Turkey, Malta and the Philipines for his youthful good looks, rock star energy and bold statements on the need to slash greenhouse gas emissions and help Syrian refugees.
But he is expected to face a more critical opposition when he unveils his Liberal party's legislative agenda Friday in a speech to be delivered by the governor general in parliament.
"Overall, I think the Liberal government has had a good start," Thomas Juneau, a public and international affairs professor at the University of Ottawa, told AFP.
"They hit the ground running. But obviously the hardest remains to be done."
Trudeau, 43, has promised deeper cuts to carbon emissions than his Tory predecessor, Stephen Harper.
He said he would withdraw Canadian fighter jets from the US-led coalition fighting the Islamic State group in Iraq and Syria, and urged Canadians to open their homes to 25,000 Syrian refugees.
Now he must negotiate a national CO2 target with Canada's regions, which share responsibility for the environment with Ottawa, and show allies he is still committed to the fight against the IS group.
Already, Trudeau has backpedalled on his promise to resettle 25,000 Syrian refugees by year's end, citing logistical problems. Most will now arrive early next year.
As well, the new prime minister faces a hostile Senate, and economic setbacks.
"The challenge for the new government," professor Peter Loewen of the University of Toronto told AFP, "is that the Liberals made a lot of promises" and the ground is shifting beneath them.
"The ability of the government to reconcile election promises with fiscal reality will be the key measure of his success," he said. "But reconciling those could be tough without giving up on some of them, for example, with the economy not being as rosy as hoped."
The economy exited a mild recession -- triggered by a plunge in oil prices -- in the third quarter ending September 30. But growth will remain weak through 2016, according to the government statistical agency.
Meanwhile, tens of thousands of oil sector workers are still unemployed.
Tory opposition leader Rona Ambrose accused the Liberals of already racking up deficits and spending recklessly after the parliamentary budget office rejected the new government's fiscal outlook, saying it was too optimistic.
- Leaving allies in lurch? -
Ambrose was also critical of Trudeau's decision to withdraw six fighter jets from the anti-IS coalition, saying Canada is "leaving our allies to do the heavy lifting."
Publicly, allies have said they understood that Trudeau must fulfill his electoral commitment to withdraw the CF-18 fighter jets from the Middle East.
But Canada will undoubtedly face pressure to swap in other military capabilities in short order, said Loewen, after France, Britain and the United States stepped up their offensive against the IS group.
Alternatively, Trudeau could simply wait until the current mission expires in March to withdraw the planes.
"By doing this, Trudeau can say he is respecting our commitment to an important mission," while taking the time to consider how best to recast Canada's role in the US-led coalition, Juneau said.
The third party in the House, the New Democratic Party, has been less critical of the Liberals -- so far.
"We're listening carefully when the new government says that it's going to have a plan in 90 days, an ambitious plan to reduce greenhouse gases in Canada," said leader Thomas Mulcair.
He said the New Democrats will support measures to reduce CO2 emissions, but added: "We need a plan. We need clear targets. We need a reporting mechanism, and we need a clear timeline."
The Liberals have offered few details as yet.
Getting all 13 provinces and territories to agree on a national climate plan will not be easy because their priorities differ and some rely on the oil and gas sector to fuel their economies.
"It's a hard circle to square," said Loewen.