By Paul Reynolds
World Affairs correspondent, BBC News website
Gordon Brown's talks with President George W Bush will set a new tone for US-British relations after years of exceptionally warm ties between Mr Bush and the UK former Prime Minister Tony Blair.
Gordon Brown: seeking a new US relationship
The expectation generally is that the UK will continue to be close to the United States but perhaps not quite as close as it was.
The new British leader is an Atlanticist, who knows and likes the US well. He is expected to - and indeed he and Foreign Secretary David Miliband have said he will - continue to advance a foreign policy that is sympathetic towards the US.
But nobody thinks that Gordon Brown is going to find a soulmate in George Bush as Tony Blair did. That relationship was forged in the heat of 9/11 and Iraq.
On the most immediate foreign policy issue to hand, Britain will not undertake a precipitous withdrawal from Iraq. However Mr Brown has spoken of a "new stage" and the signs are that he wants out as soon as possible, as long as that is (or can be presented as being) compatible with the policy of handing over only when the Iraqis can do the job.
And Britain will stay in Afghanistan in a combat role. Indeed, it wants more Nato members to join the fray, as does the United States.
A key issue that might well test the relationship is Iran. A new round of UN sanctions is going to be debated, maybe decided, in September, but what if the Bush administration decides to attack Iran's nuclear facilities in the final 18 months or so of its term of office?
Mr Brown has not ruled out military action - doing so now could undermine the diplomatic and economic pressure currently being applied, it is felt - but most observers think he would not join in if the US went ahead.
Mr Brown will go to Camp David on Sunday evening for dinner and will stay over into Monday, the White House spokesman Tony Snow has announced.
Forged in fire: Bush and Blair at Camp David, February 2001
He will no doubt try to clear up some mixed signals that his government has sent out about how it wants to deal with Washington. For example, the appointment of Mark (now Lord) Malloch Brown as Foreign Office minister - a man who was a leading critic of the Bush administration when he was a senior UN figure - was seen as a deliberate distancing from the US neo-conservatives.
On the other hand, Britain does not really want to get much closer to the European Union, holding firm to its "red lines" in the EU treaty negotiations, one of which is to preserve a national foreign policy. This approach was reflected in the recent row with Russia in the Litvinenko affair, in which London did not reach out for an EU-wide response but trod its own path.
The possibility is that Britain will end up semi-attached to the United States and semi-detached from Europe.
Links to US
The former British ambassador to Washington, Sir Christopher Meyer, was present at Camp David when Tony Blair met George Bush there in February 2001. He dismisses any suggestion that Gordon Brown will want to use Camp David to distance himself significantly from President Bush.
"People have got quite excited about this," he said. "There are thousands of seminars about it but I don't think that it warrants that level of activity. They will not be as close personally, unless some magic strikes, but frankly that does not matter that much.
"There is such an awful lot of stuff in the relationship and while there are variables - personalities, events, and shifts of tone - and sometimes the relationship is not that special, historically since 1945 it goes on regardless.
One recent example of how the relationship can at times be tense came when a House of Commons committee revealed that Britain had reservations about aspects of the US policy of flying terror suspects around the world but that these were ignored.
It was a reminder that, although the two countries are as close allies as they can realistically be, in the end they can diverge.
"Mr Brown's mixed signals are a classic case of an administration bedding in, with some of the bits not dropping into place," says Sir Christopher.
"As for Iran, I am not sure I see the UK going for military action. There are major military objections. I would be surprised if Britain got involved.
"And in Afghanistan, we need help. How long can we sustain that action?"