LONDON, England (CNN) -- U.S. Democratic presidential candidate Barack Obama met with British Prime Gordon Brown on Saturday on the last leg of his weeklong overseas tour.
U.S. presidential candidate Barack Obama leaves 10 Downing Street on Saturday.
The two discussed foreign policy issues and the "special relationship" between Britain and America during two hours of talks inside 10 Downing Street, the prime minister's London residence.
The pair made the most of the sunshine by sitting outside on the patio, even taking a stroll toward adjacent St. James's Park, much to the surprise of nearby tourists.
"The prime minister's emphasis, like mine, is on how we can strengthen the transatlantic relationship to solve problems that can't be solved by any single country individually," Obama said outside Downing Street after the meeting.
Those problems, Obama said, include climate change, international terrorism and turmoil in world financial markets. Obama and Brown also discussed cooperation in resolving the problems in the Middle East and burden-sharing in Iraq and Afghanistan.
Earlier, Obama met with former British Prime Minister Tony Blair, who now serves as the Middle East envoy for the "quartet" of the United States, the European Union, Russia and the United Nations. Watch more on Obama's visit to London »
After his meeting with Brown, Obama met with opposition leader David Cameron, head of the Conservative Party, before heading back to the United States.
During the meeting, a camera microphone picked up some light banter between the two men about Obama's current state of fatigue.
Cameron told the candidate, "You should be on the beach. ... You need a break. ... You need to be able to keep your head together."
Obama told Cameron he would try to take a week off in August. He said he got advice from a Clinton White House veteran on how to handle the demands on his time.
"Somebody who had worked in the White House -- not Clinton himself -- but somebody who had been close to the process, said that [should we be successful] ... the most important thing you need to do is to have big chunks of time during the day when all you're doing is thinking. And the biggest mistake that a lot of these folks make is just feeling as if you have to be ..."
Cameron interjected, "These guys just chalk your diary up." Obama agreed: "Right, exactly, in 15-minute increments."
Cameron told him: "We call it the dentist waiting room. You have to scrap that, because you've got to have time." Obama said that not taking a break is when "you start making mistakes or you lose the big picture."
Obama's trip has taken him through the Middle East and Europe, starting with Afghanistan, Iraq, Jordan, Israel and the West Bank and finishing with Germany, France and Britain.
Though Obama joked with the British press that London was the highlight for him, his trip has included several other moments that have garnered positive international headlines, most recently a Friday news conference in Paris with French President Nicolas Sarkozy and a speech in Berlin on Thursday to about 200,000 people.
The Democratic candidate admitted that his ratings may have slipped in the United States since he's been away, as Americans focus more on domestic problems like gas prices and home foreclosures than on his travels abroad. But he said he still considers the trip important.
"The reason that I thought this trip was important is that I am convinced that many of the issues that we face at home are not going to be solved as effectively unless we have strong partners abroad and unless we get a handle on Iraq and Afghanistan," Obama said.
The military efforts in Iraq and Afghanistan, he said, are costing America money that could be better spent on rebuilding the U.S. economy.
"This was important for me not only to try to highlight or amplify how the international situation affects our economy back home but also hopefully to give people at home and also leaders abroad some sense of where an Obama administration might take our foreign policy," he said. Watch Obama's complete interview with CNN's Candy Crowley »
Obama's staff has repeatedly said that the tour is not political and not intended as a campaign trip, although Obama's meetings with troops and world leaders were designed to boost his foreign policy credentials and help voters back home envision him as commander in chief.
The warm atmosphere in Paris -- where Sarkozy repeatedly called Obama a friend -- continued in London, and not just because of the warm summer temperatures that finally settled on the British capital this week. Watch France's obsession with Obama. »
Obama and Brown were shown laughing and smiling as they walked together, and Obama reiterated to reporters that the special relationship between Britain and America continues.
"I think there's a deep and abiding affection for the British people in America and a fascination with all things British that is not going to go away any time soon," Obama said.
In a radio address Saturday, presumptive Republican candidate Sen. John McCain took aim at Obama's "long-distance affair."
"With all the breathless coverage from abroad, and with Sen. Obama now addressing his speeches to 'the people of the world,' I'm starting to feel a little left out. Maybe you are, too," McCain said.
Britain was a low-key stop on Obama's itinerary, in part because no major events were planned. Brown also decided not to greet the U.S. senator on the doorstep of 10 Downing Street because he didn't grant the same honor to McCain when the Republican visited in March.
That protocol comes at a difficult time politically for the British prime minister, who could have benefited from a photo opportunity with a man so hugely popular in Europe. Brown's Labor Party lost a local election this week in what had been considered safe territory for the party, adding to existing political woes for Brown and raising questions about his future as prime minister.
Asked by a British reporter whether he had any advice for Brown, Obama said no -- but he said elected officials must always be prepared to deal with a fickle public.
CNN's Ed Hornick, Steve Brusk and Sasha Johnson contributed to this report.