Mitt Romney speaks at an Ohio campaign event on July 18: A theory being tossed around to explain why the GOP candidate still refuses to release tax returns before 2010 is that his finances were so hurt after the 2008 economic collapse that he paid no taxes in 2009.

J.D. Pooley/Getty Images

• The return of Mitt Romney
• Oscar acceptance speeches: Does Oprah get thanked more than God?
• The era of cheap airfares just ended

resumptive GOP presidential nominee Mitt Romney got himself into hot water on the British leg of a six-day trip that will also take him to Poland and Israel, telling NBC that he saw "disconcerting" problems with security and immigration staffing at the London Summer Olympics. "It's hard to know just how well it will turn out," Romney said. That caused British Prime Minister David Cameron to vow that "Britain can deliver," while also tweaking Romney, who ran the 2002 Salt Lake City Olympics, by saying that London is "one of the busiest, most active, bustling cities anywhere in the world," and that "of course it's easier if you hold an Olympic Games in the middle of nowhere." On Thursday, Romney met with Cameron and other top British officials, and tried to steer away from controversy. "It is impossible for absolutely no mistakes to occur" at the games, Romney said, but such mistakes "are all overshadowed by the extraordinary demonstrations of courage, character, and determination by the athletes."