Republican John McCain chided presidential rival Barack Obama for his highly-publicized international trip on Saturday, as the Democrat defended the largely well-received tour, saying in London that some US problems can only be solved through alliances overseas. Obama wrapped up a week-long tour, including stops in Iraq, Afghanistan, Israel and Europe, designed to reassure American voters that he can handle international politics and mend relations with key allies frustrated with eight years of President George W. Bush. McCain has tried to portray his rival as naive and inexperienced on foreign policy and national security, but suggested Saturday that Obama was ignoring US voters during his time abroad. The former Vietnam prisoner of war has struggled this week to get back the media spotlight as he campaigned on pocketbook issues in the US Midwest. Obama was met by a crowd of 200,000 people in Berlin and earned good reviews for his Middle East stops, but he acknowledged that he could slip in the polls because of American voters' concerns about domestic issues. McCain took a swipe at his rival in his weekly radio address on Saturday. "With all the breathless coverage form abroad, and with Senator Obama now addressing his speeches to the people of the world, I'm starting to feel a little left out. Maybe you are too," he said. Republicans have criticized Obama throughout his trip, and McCain's campaign said recently the Democrat was taking a "premature victory lap" with more than 100 days remaining before the November election. But Obama sought to turn that back on his critics. He said McCain had earlier been "telling me I was supposed to take this trip. He suggested it and thought it was a good idea." "John McCain has visited every one of these countries post-primary that I have," he said in London. "So it doesn't strike me that we have done anything different than the McCain campaign has done, which is to recognize that part of the job of the next president, commander in chief, is to forge effective relationships with our allies." Obama, who spoke to reporters Saturday after wrapping up talks with British Prime Minister Gordon Brown, said he would not be surprised if there was a dip in some of the polls in the week since he left home since American voters' primary worries are rising gas prices and home foreclosures. "The reason that I thought this trip was important is that I am convinced that many issues that we face at home are not going to be solved as effectively unless we have strong partners abroad," the Democratic senator said. "And unless we get a handle on Iraq and Afghanistan, not only are we going to be less safe, but it's also going to be a huge drain on resources." At the same time, he said the journey to war zones in Iraq and Afghanistan, the Mideast and Europe was important because "many of the issues that we face at home are not going to be solved as effectively unless we have strong partners abroad." In his radio address, McCain continued to hammer Obama on his opposition to sending more troops to Iraq in the so-called "surge." "Now that it's clear that the surge has succeeded, and brought victory in Iraq within sight, Sen. Obama can't quite bring himself to admit his own failure in judgment," he said. "Even in retrospect, he would choose the path of retreat and failure for America over the path of success and victory." McCain on Friday laid out a vision of near-apocalypse he said could have occurred had Obama managed to stop the troop buildup ordered by Bush, a move that was unpopular with the American people. The veteran Arizona senator described a domino chain of calamity: US forces retreating under fire, the Iraqi army collapsing, civilian casualties skyrocketing, al-Qaida killing Sunni leaders and finding havens to train fighters and launch attacks on Americans, and civil war, genocide and conflict across the Middle East. "Above all, America would have been humiliated and weakened," he said during a campaign stop in Denver. "Terrorists would have seen our defeat as evidence America lacked the resolve to defeat them. As Iraq descended into chaos, other countries in the Middle East would have come to the aid of their favored factions, and the entire region might have erupted in war." Obama opposed the "surge," and has called for a withdrawal from the unpopular Iraq war over 16 months. He has said the Iraq invasion was an unwise move that distracted from the efforts to find Osama bin Laden and other terrorist leaders and to root out the Taliban forces in Afghanistan. Obama's trip began with a tour of the war zones in Iraq and Afghanistan, visits to Jordan, Israel and the Palestinian Authority, and included stops in Germany and France. In London on Saturday, Obama met with Brown, Middle East envoy and former British Prime Minister Tony Blair, and Conservative Party leader David Cameron. Obama said he and Brown discussed a wide range of issues, such as climate change, terrorism and financial markets. Obama now heads back to the United States, where economic issues are again expected to dominate the campaign. He has a campaign speech scheduled Sunday to a national convention of minority journalists on his home turf of Chicago.