US presidential hopeful Mitt Romney has found himself the target of jokes in Britain after London's mayor Boris Johnson mocked comments he made about preparations for the 2012 Olympics.
Hours after arriving for a visit designed to boost his foreign policy credentials, Romney surprised his British hosts by saying there were "disconcerting" reports about London's ability to stage the games.
Although Romney backtracked later after talks with British Prime Minister David Cameron, his comments left a sour taste.
Addressing a crowd of 60,000 gathered in London's Hyde Park for a pre-Olympics concert, Mayor Johnson said on Thursday: "There are some people who are coming from around the world who don't yet know about all the preparations we've done to get London ready in the last seven years.
"I hear there's a guy called Mitt Romney who wants to know whether we're ready. Are we ready?"
The crowd roared "yes".
Romney, who will attend the opening ceremony on Friday, had questioned Britain's security preparations for the Games and said a now-cancelled strike by border officials was "not encouraging".
Before holding discussions with the Republican candidate, Cameron took an apparent swipe at Romney's past role as head of the 2002 Winter Olympics in Salt Lake City.
"We are holding an Olympic Games in one of the busiest, most active, bustling cities anywhere in the world," Cameron said at a press conference in the Olympic Park.
"Of course it's easier if you hold an Olympic Games in the middle of nowhere."
Romney's overseas trip will also take him to Israel and Poland.
His first official appearance during the swing was with Cameron, but he also met Tony Blair, the former prime minister, Nick Clegg, the deputy prime minister, and Ed Miliband, the leader of the opposition Labour Party.
Romney, a former private equity executive whose decades in private business gave him ample exposure to international affairs, is a former one-term governor of the state of Massachusetts untested on the world's political stage.
To that end, he hopes to persuade voters back home that he is no novice on foreign affairs and that they should elect him as president in a complex, dangerous world.
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Romney will spend part of his time in London raising money and highlighting a key part of his resume - the successful Salt Lake City Olympics he managed - with an appearance on Friday at the opening ceremonies of the London Games.
The meetings come a day after the Daily Telegraph newspaper published a story quoting an unidentified Romney campaign adviser saying the Republican believes the US relationship with Britain is special because of shared "Anglo-Saxon heritage" and that the White House does not appreciate that shared history.
Romney, however, quickly distanced himself from any such view.
"I don't agree with whoever that adviser might be, but do agree that we have a very common bond between ourselves and Great Britain," Romney told NBC News.
Nonetheless, Joe Biden, the US vice-president, and top Obama aides criticised Romney.
"The comments reported this morning are a disturbing start to a trip designed to demonstrate Governor Romney's readiness to represent the United States on the world's stage," Biden said.
Later on Thursday, Romney planned to hold a high-dollar fundraiser at the Mandarin Oriental hotel in London's Knightsbridge district.
One of the hosts of that fundraiser, former Barclays CEO Bob Diamond, withdrew from the event after he resigned in the wake of a rate-rigging scandal rocking British banks.