President Barack Obama risks being tripped by over-inflated expectations as he departs Washington tonight for a tour that starts with talks with King Abdullah in Saudi Arabia tomorrow but will be dominated by his long-advertised address to the Muslim world in Egypt on Thursday.
It is Mr Obama's second major trans-Atlantic foray, following his visits to the G20 and Nato summits in April. As well as the Middle East, he will dip once more into European diplomacy, visiting the former concentration camp at Buchenwald in Germany and attending weekend ceremonies to mark the 65th anniversary of the D-Day landings. Beyond the pageantry, he is due to hold private bilateral talks with the leaders of France and Germany.
But it is at Cairo University that Mr Obama, while blessed with undoubted rhetorical skills, faces the biggest challenges. He first promised all the way back in 2007 to deliver an address to the world's 1.5 billion Muslims if he were to become President. This will be that moment, even though he gave something of a preview when he spoke of a new era of "mutual respect" between Muslims and the US in Istanbul at the end of his last trip.
Aides have been working to downplay expectations, insisting that the speech will include no new concrete initiatives and will be more general in nature. "I want to use the occasion to deliver a broader message about how the United States can change for the better its relationship with the Muslim world," Mr Obama said last week after meeting the Palestinian President, Mahmoud Abbas, in Washington.
This all on its own may disappoint Muslims in the Arab world and beyond, who are looking for evidence of real change from an America that many grew to despise during the Bush years, when its military invaded Afghanistan and Iraq and was exposed for prisoner abuse at Abu Ghraib prison.
The President is certain to try to separate himself from George Bush, if only by stressing his own personal connections to the Islamic world, such as having people of the Muslim faith in his own family, including his late father from Kenya, and spending part of his childhood in Indonesia, the most populous Muslim nation in the world.
But in Cairo, where an extraordinary security clampdown is taking place ahead of his visit, Mr Obama will find himself pursuing several goals at once. His audience will want to hear first what he can do to revive still-stalled progress towards an Israeli-Palestinian settlement. Imparting new momentum towards attaining a two-state solution will be the focus of his talks tomorrow in Riyadh as they were at meetings with regional leaders including the Israeli Prime Minister, Benjamin Netanyahu, and President Abbas at the White House in recent weeks.
But Mr Obama will also be seeking a regional consensus in the Middle East on dealing with the nuclear ambitions of Iran and countering the threat of extremist terrorism within groups like the Taliban and al-Qa'ida.
The President also faces dilemmas born of his decision to deliver the speech in Cairo, which is historically the cradle of Islamic intellectual thought. He will be aware of the record of his host, President Hosni Mubarak, in repressing political freedoms during the 28 years of his rule.
The White House this week said that among those invited to attend his speech will be "political actors" in Egypt, a list that is likely to include activists who are opposed to President Mubarak's regime.
The danger that Mr Obama will disappoint is widely recognised. "The best he could hope to accomplish is to move Arab public opinion about the United States and make it easier for their governments to work with Washington. We need it for our general influence in the area," noted Elliott Abrams, from the Council on Foreign Relations in New York.
Handicapping Mr Obama will be the absence of any real evidence that he is succeeding in moving the Israeli-Palestinian peace process forward. He has notably failed, for example, to persuade Israel to stop construction of new settlements in the occupied West Bank, even after the glad-handing with Mr Netanyahu at the White House.
"How the United States addresses the conflict is how citizens of the region are likely to regard the United States," said Steve Grand, an expert on US-Islamic relations at the Brookings Institution. Mr Obama, he went on, "has been great at a rhetorical level, but he has to provide details about what the United States is going to concretely do to reach out to the Muslim world."
The security apparatus of Egypt is on high alert. To prepare for Thursday's visit by Mr Obama, it has conducted a huge security sweep of the streets that the motorcade will travel on the way to the university campus.
"It's a massive security operation, the biggest we have seen yet," a security official in Egypt said yesterday. Hundreds of students have also been rounded up for questioning ahead of the speech.
Since taking office, Mr Obama has taken steps designed to ease suspicions of the US in the Muslim world, including his order on his first day in office to close the Guantanamo complex within one year.
The first television interview he gave after taking office was to the Arab-language network Al-Arabiya. He recorded a video message speaking directly to the Iranian people to mark Nowruz, the Iranian New Year, and has made overtures to the regime in Tehran about improving relations and ending the nuclear stand-off.