Senior advisers to Mitt Romney have bitterly criticised David Cameron's recent White House "love-in" with Barack Obama before Romney's first visit to London for the opening of the Olympic Games.
Referring to Cameron's highly flattering toast to Obama during a banquet given in the prime minister's honour when he visited Washington in March, a senior aide said: "You don't take sides in an election year".
The aide, who requested anonymity, said Romney and his wife, Ann, would attend the "first day of activities" of the 2012 Games, which open in July. Romney would do "one or two other things" while in London. A meeting with Cameron was not ruled out, but that was "up in the air", the aide said.
Doubts about a possible Downing Street meeting appear to stem in part from surprise and dismay felt in the Romney camp about what it saw as Cameron's obsequious behaviour at the banquet on 14 March.
Cameron's performance smacked of a "lack of experience" and was seen as "not very skilful", the aide said.
Romney advisers responsible for European policy were said to have been so alarmed that their initial reaction was to complain Cameron had "infringed" the special relationship between the US and Britain.
"It's curious. What Cameron did is ironic, seeing that a few days later Obama said he was neutral on the Falklands. Cameron was taken for a ride by Obama," the aide said.
He said he had been telephoned the following day by an embarrassed British contact who told him: "'I don't want to talk about it [Cameron's toast]. I'm just sorry it happened.'"
Criticism from Romney's camp is unusual. It prides itself on being extremely disciplined, careful in its dealings with the press, and averse to controvery.
US campaign teams tend to be extremely sensitive about any interventions by foreign leaders in domestic politics. In the run-up to the 2008 election , John McCain's campaign complained to the British embassy about an article by Gordon Brown praising Obama.
The same year, the Obama campaign took issue over a leaked memo from the British embassy in Washington mildly critical of Obama: lingering resentment carried over from election headquarters in Chicago to the White House.
In his speech Cameron thanked the US president for his "strong and beautiful words" about Anglo-American ties, and said Obama "has pressed the reset button on the moral authority of the entire free world".
Apparently acknowledging their differing political outlook, Cameron went on: "You don't get to choose the leaders that you have to work with. But all I can say is that it is a pleasure to work with someone with moral strength, with clear reason and with fundamental decency in this task of renewing our great national alliance for today and for the generations to follow."
Cameron was heavily criticised in British papers such as the Telegraph and Daily Mail for this perceived extravagant praise of Obama.
Romney's London visit is likely to be his first trip abroad after securing the Republican party's presidential nominee. He will be formally selected at the party's national convention in Tampa, Florida in late August, thereby teeing up what is expected to be a tough, tight fight to unseat Obama.
Romney has scant experience of foreign affairs or foreign policy, so in theory a visit to London should be a relatively safe first step. But Cameron's outspoken support for Obama may have tainted the relationship before it has begun.
Obama, too, had little foreign policy experience before becoming president, and visited Europe mainly to obtain pictures of himself abroad, visiting foreign leaders, important in an election campaign. He drew a massive crowd in Berlin, but Romney does not have that kind of pulling power.
Romney's presence at the Olympics stems from his presidency of the 2002 Winter Olympics organising committee in Salt Lake City, when he helped rescue the event from financial problems and a corruption scandal. "Ever since the games in Salt Lake City in 2002, the Olympics has been a big part of my life," he told a radio station in Columbus, Ohio last month.
In a statement Romney said: "The greatness of achievement is measured in the fire and passion of dreamers. The 2002 Olympic Games taught us that our aspirations can become reality."