"There are some people coming from around the world who don't yet know if we are ready," the London mayor said. "There's a guy called Mitt Romney who wants to know whether we are ready. Are we ready? Yes we are!"
The assembled crowd then erupted into cheers.
Johnson's comments came after Romney said Wednesday during an interview with NBC "It's hard to know just how well [the London Games] will turn out."
“There are a few things that were disconcerting: the stories about the private security firm not having enough people, supposed strike of the immigration and customs officials — that obviously is not something which is encouraging," Romney said.
The presumptive Republican nominee went on to question British enthusiasm for the games.
“Do they come together and celebrate the Olympic moment?” he asked. “That's something which we only find out once the games actually begin.”
Prime Minister David Cameron shot back ahead of the pair's meeting Thursday morning, defending London's handling of the games — and swiping Romney's efforts in Salt Lake City.
“We can't say to people that life is going to be completely as normal — it isn't,” he said. “This is an extraordinary few weeks for our city, for our country, and I think people have to be prepared for some difficulties as a result of that. We are holding an Olympic Games in one of the busiest, most active, bustling cities anywhere in the world. Of course, it's easier if you hold an Olympic Games in the middle of nowhere.”
Later Thursday, Romney looked to repair damage from his remark during a press conference.
“My experience with regards to the Olympics, is it is impossible for absolutely no mistakes to occur. Of course there will be errors from time to time, but those are all overshadowed by the extraordinary demonstrations of courage, character and determination by the athletes," Romney said, referencing a question about early missteps at the Olympics — and implicitly his earlier criticism.
"The games are, after all, about the athletes, the volunteers and the people of the community that come together to celebrate those athletes. They are not about the Organizing Committee. And as soon as the sporting events begin, we all forget the organizers and focus on the athletes.”