U.S. President Donald Trump has embarked on a nine-day diplomatic obstacle course that offers both opportunity and peril for a president eager to change the subject as scandal rages back home.

Indeed, Mr. Trump's flight to Saudi Arabia had just begun on Friday afternoon when The Washington Post reported that a White House official is a significant person of interest in the probe into possible co-ordination between Russia and Mr. Trump's campaign team. Mr. Trump has said there was "zero" collusion.

Minutes later came a report in the New York Times that Mr. Trump had told Russian officials during an Oval Office meeting this month that firing James Comey as director of the U.S. Federal Bureau of Investigation relieved "great pressure" on him. The paper cited an internal document summarizing the meeting, during which Mr. Trump described Mr. Comey as "crazy" and "a real nut job."

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No president in recent memory has been as reluctant leave the country as Mr. Trump. His predecessors made early visits to Canada, Mexico and elsewhere, but he has demurred, preferring to have foreign leaders come to him. That raises the stakes for this trip, which is longer and more complicated than the traditional presidential debut on the world stage.

On Friday morning, hours ahead of his departure, he reasserted his "America First" vision of international affairs. "Getting ready for my big foreign trip," he wrote on Twitter. "Will be strongly protecting American interests – that's what I like to do!"

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Mr. Trump is a man of habit, who has not spent a night anywhere other than the White House or a property he owns since his inauguration. In Saudi Arabia, his first of five stops, his hosts will prepare his favourite meal – steak with a side of ketchup – in addition to local delicacies.

But even the most solicitous of hosts cannot insulate Mr. Trump from the difficult diplomatic balancing act that awaits him.

In Saudi Arabia, Mr. Trump is scheduled to deliver a speech aimed at the Islamic world after running a campaign marked by anti-Muslim rhetoric. In Israel, he will meet with Prime Minister Benjamin Netanyahu, days after he reportedly shared top-secret Israeli intelligence with Russia. In Rome, he will visit the Pope, the popular, liberal-minded pontiff whom he denounced during the election campaign.

Then, in Brussels, he will participate in a summit at the North Atlantic Treaty Organization, an alliance whose utility he repeatedly questioned before reversing himself. And in Sicily, he will join fellow leaders of the Group of Seven nations, some of whom are deeply unsettled by his approach to world affairs.

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It is an itinerary that would tax any president and his staff. The difficulty is further magnified by the fact that Mr. Trump is embroiled in an uproar over allegations of Russian interference in the U.S. election and his firing of Mr. Comey on May 9.

"This is a White House that is going to have to walk and chew gum at the same time, when it has already shown an inability to walk very far without tripping," said Jon Finer, who was the chief of staff to former secretary of state John Kerry.

Mr. Trump and his staff will have to grapple with any crisis that pops up back in the United States or elsewhere and still focus on the business at hand, all while they are jet-lagged and far from the support structures in Washington.

The initial portion of Mr. Trump's trip – which includes visits to Riyadh, Jerusalem, Bethlehem and the Vatican – is packed with religious symbolism and is intended to send a message of unity. Mr. Trump's powerful senior adviser, his son-in-law Jared Kushner, led a West Wing team to craft the agenda.

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On Sunday, Mr. Trump is scheduled have lunch with the leaders of more than 50 predominantly Muslim nations. There he will deliver an address whose goal is to bring together "the broader Muslim world against common enemies of all civilization," according to national security adviser H.R. McMaster.

During the campaign, Mr. Trump said, "Islam hates us," vilifying a religion practised by millions of Americans. In his first week as President, he signed an executive order banning citizens of seven Muslim-majority nations from entering the United States, a move the courts later blocked, partly on the grounds that it represented a form of religious discrimination. One of the chief architects of the ban, policy adviser Stephen Miller, is reportedly drafting Mr. Trump's speech for Sunday.

With that backdrop, Mr. Trump benefits from low expectations, said Shadi Hamid, a senior fellow at the Brookings Institution in Washington who is an expert on political Islam. "The messenger is problematic," Mr. Hamid said, but "as long as he doesn't say something terribly offensive, it will be seen as a success."

While leaders in the Middle East are likely to greet Mr. Trump warmly, he could receive a cooler reception in Europe. Although the Pope has said he would "never make a judgment about a person without hearing them out," other public figures on the continent have issued sharp criticisms of Mr. Trump. That includes France's newly elected President, Emmanuel Macron, who denounced Mr. Trump's musings on abandoning the Paris climate treaty, a likely point of contention at the G7 meeting in Sicily.

With a report from the Associated Press