David Cameron will deliver a powerful reminder when he arrives in Washington today that the days are long gone when the Conservative and Republican parties were viewed as transatlantic cousins.
The Prime Minister will be feted by Barack Obama, be guest of honour at a state dinner and even accompany the Democrat President to a basketball match. By contrast, he will not even meet any of the Republican candidates for the presidency – Mitt Romney, Rick Santorum, Newt Gingrich and Ron Paul.
British officials stressed yesterday that none of the quartet, who will be away from Washington this week campaigning, had requested a meeting with Mr Cameron. He is expected to be introduced to senior Republicans, including John Boehner, the Congress speaker, and Senate Republican leader Mitch McConnell at the banquet.
However, he will be careful to do nothing that can be construed as boosting the party's cause in the race for the presidency. Things could not be more different from two decades ago when Margaret Thatcher and Ronald Reagan appeared to act as a mutual political admiration society. Senior Tories flew stateside to help the campaigns of George Bush Sr, Bob Dole and George Bush Jr, while their Labour counterparts were often on the same planes heading to canvass for the Democrats.
The historic relationship between the Republicans and Tories suffered a heavy blow in 2004 when the younger Bush banned the Tory leader, Michael Howard, from the White House during a visit to Washington. The snub – retribution for Mr Howard's criticism of Tony Blair over the failure to find weapons of mass destruction in Iraq – still resonates.
Meanwhile, the political gravity in the Republican Party has drifted to the Right at the same time that Mr Cameron has mounted a determined effort to increase his party's appeal to the centre ground, particularly on social issues.
This is typified by the Prime Minister's commitment to legislate for same-sex marriages. Such a view would be electoral poison among Republicans: high-flying Mr Santorum has compared homosexuality to "man-on-dog" sex. There is also the political calculation among senior Tories that Mr Obama is a winner – and is likely gain a second term in office regardless of his opponent in November.
That message will have been relayed to London by British embassy officials who are carefully monitoring the Republican race: one was spotted taking notes at a recent Santorum rally in Ohio. Lots of younger Conservatives supported him in 2008 and are likely to do so again next time around.