While wife Michelle attracted breathless attention with every stop, fashionable outfit and sip of tea.
The new U.S. president, in London for Thursday's high-stakes global summit on the financial meltdown, dashed through a dawn-to-dark schedule Wednesday despite the effects of a head cold.
School children ran alongside his nearly 20-vehicle motorcade.
He was asked to give a pep talk to England's soccer team for its World Cup qualifying match (he politely declined) and to offer campaign tips to embattled British Prime Minister Gordon Brown ("good policy is good politics," he said).
There was even a chance to talk dinosaurs with Brown's young sons -- and to snare two hours of quality time with Queen Elizabeth II at Buckingham Palace.
"Michelle has been really thinking that through," Obama said, presumably referring to the daunting clothes dilemma posed by an audience with royalty. Mrs. Obama chose a black skirt and sweater over a white top and a double strand of large pearls.
Before that meeting at the palace: diplomacy of a different sort.
Brown, his dour demeanor one factor in his shaky political standing, said effusively that Obama had provided "renewed hope" all around the world. Russian President Dmitry Medvedev, whose nation has often assailed the U.S., offered his own praise, albeit more measured. His first meeting with Obama, he said, left him "far more optimistic" about Washington-Moscow relations. Undeterred by his cold, Obama held a whirlwind of one-on-one talks with those and other leaders, including Chinese President Hu Jintao. He aimed not just to lay the groundwork for Thursday's summit of the 20 largest wealthy and developing economies but also more broadly to initiate a new era in American foreign relations.
His first task was a little repair job.
British feelings were hurt by what was perceived as a bit of a cold shoulder from Obama toward Brown when the British leader visited Washington last month. So when Obama and Brown appeared together before American and British reporters, Obama bent over backward to show his affection for both host and host country. The lengthy round of questions made up for the slight of no news conference in Washington, and Obama took special care to note that the talks with Brown were his first official stop on his first overseas trip.
"The United States and the United Kingdom have stood together through thick and thin, through war and peace, through hard times and prosperity, and we've always emerged stronger by standing together," Obama said next to a beaming Brown.
Nevertheless, Obama hedged his bets by also sitting down -- in full view of the cameras -- with Brown's main rival, David Cameron, the leader of Britain's Conservative Party.
Obama's talks with Medvedev were their first in person. Both sides sought to portray them as a major development for a relationship that has been severely hobbled in recent years by ever-sharpening disputes over the U.S.-led Iraq invasion, a Bush administration proposal to build a new missile defense system in Eastern Europe, enlargement of NATO into what Moscow considers its sphere of influence, and Russia's devastating war last year with its neighbor and former Soviet republic Georgia.
"We believe that the time has come to reset our relations, as it was said, and to open a new page," Medvedev declared at Obama's side.
The leaders announced new arms control talks aimed at reaching a deal to slash both nations' stockpiles of nuclear warheads.
Obama also announced he would visit Moscow in July. The leaders made clear they want the broad outline of a deal by then to give enough time for legislative approval.
The U.S. president cast the effort as important on its own, calling nuclear weapons that could find their way into terrorists' hands "the gravest threat to humanity." He also said that producing a tangible agreement is a "good place to start" in setting the stage for cooperation on thornier areas such as Iran, North Korea, and Afghanistan.
Obama's meeting with Hu brought yet another announcement of foreign travel. The White House said the president would go to China in the second half of the year.
The leaders announced a new mechanism for U.S.-China dialogue that is intended to broaden discussion and give it fresh weight. They also shared concerns about North Korea's stated plans for a rocket launch suspected to be a cover for a missile test.
On a lighter note, Obama gave Queen Elizabeth II an engraved iPod during his visit to Buckingham Palace. The portable music device came with headphones and loaded with dozens of classic show tunes -- including several from "Camelot," based on the King Arthur legend, and "My Fair Lady," set in London. The president and first lady also gave the queen a rare book of songs signed by "The King and I" composer Richard Rodgers.
As the Americans arrived at the palace, a few thousand wellwishers cheered and waved as their limousine went past.
In central London's financial district, by contrast, thousands of protesters rallied against the economic summit.
Who's to blame for the global crisis? Obama acknowledged U.S. mistakes but also defended America's leadership and its economic model against predictions of decline.
"I think if you pulled quotes from 10 years ago, 20 years ago, 30 years ago, from previous news reports, you might find similar contentions that America was on decline," Obama said. "And somehow it hasn't worked out that way."