Mitt Romney's meeting with David Cameron threatened to be overshadowed by a row about the Olympics on Thursday, after the Republican presidential candidate said London's preparations for the event were "disconcerting".
Romney, who is virtually neck-and-neck in the polls with Barack Obama, met with the prime minister in No.10 Downing Street and recalled his time in charge of the 2002 Salt Lake City Winter Games.
But it got worse for Romney who, when attempting to U-turn on his comments, caused amusement when said he'd spent a great day in the "backside" of Downing Street - rather than the back garden.
Romney initially risked offending his hosts on Wednesday evening when he said he could not be sure if the British people would get behind the Games.
"You know it's hard to know just how well it will turn out," He told NBC News on Wednesday. "There were a few things that were disconcerting."
"The story about the private security firm not having enough people, the supposed strike of the immigration and customs officials, that is not something that is encouraging."
Romney also said there were "three parts" to ensuring the Olympics were a success.
"Number one is the athletes," he said. "Number two is the volunteers, they'll have great volunteers here.
"Number three, are the people of the country, do they come together and celebrate the Olympic moment? That is something we only find out once the Games actually begin."
Speaking before his meeting with Romney at a press conference in the Olympic Park, Cameron issued a rebuke to the presidential candidate.
“I think we will show the whole world not just that we come together as a United Kingdom but also we’re extremely good at welcoming people from across the world," he said.
He added: “I will obviously make those points to Mitt Romney. I look forward to meeting him.”
“This is a time of some economic difficulty for the UK but look at what we are capable of achieving as a nation even at a difficult economic time.
"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."
Speaking on the steps of Downing Street on Thursday afternoon, Romney attempted to make up for his earlier comments by saying he "applauded the work of the organising committee" of the Games.
However he raised some eyebrows when his comments that he had enjoyed looking "out the backside of Downing Street" were lost in translation.
Speaking during a meeting with Ed Miliband earlier in the day, Romney said it was "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 is due to attend the opening ceremony of the Games on Friday evening, before leaving the UK for Poland and Israel.
While in London he is also set to tap in to the reserves of wealthy Americans living in the city by hosting a fundraising dinner.
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