HE'S not the president, at least not yet, but when John McCain shakes hands with Gordon Brown in Downing Street this week, he will be doing his best to look the part.
Having secured the Republican nomination, McCain is making London the centrepiece of a European trip designed to highlight the contrast between him and the chaos engulfing his Democratic presidential rivals.
While Hillary Clinton and Barack Obama
continue a nasty battle for their party's nomination, McCain is sitting pretty and able to act the part of globe-trotting statesman.
"He's going to come across as very presidential – that's the hope," said Phillip Klein of the American Spectator.
"While he will come across as a statesman, Hillary Clinton and Barack Obama are fighting over the latest silly conversation by their supporters."
A two-day visit to London is the centrepiece of a visit that also takes McCain to Israel, Jordan and France.
Officially, he is on senate business, but not many senators get to see the prime ministers, presidents and a king on their travels.
Brown can expect an easy time of it when he sits down to tea with the Arizona senator.
McCain has put national security at the centre of his presidential campaign.
It is not known whether he will ask Britain to match his pledge to keep US troops in Iraq for "100 years", but he will be keen to rekindle the 'special relationship' among one of a dwindling band of American allies.
National security also puts him on firm ground with the Republican party, the conservative wing of which remains suspicious of McCain's liberal social policies, not least his opposition to torture at Guantanamo Bay.
McCain, perhaps anticipating his Downing Street visit, has released a campaign commercial comparing himself to Winston Churchill and playing the great man's famous "Fight them on the beaches" speech.
The wonder for McCain's foreign hosts is that, after the disasters of the Bush administration, a Republican has a decent chance of becoming the next president.
The secret lies in McCain's career as an outsider. He was not part of the Bush Cabinet, and Americans do not hold him responsible for its many failures.
"He's been known for years as a maverick," says Klein. "Swing voters are not going to see him as a Bush clone."
This week he introduced a bill into Congress to call a one-year freeze on earmarks, a system which involves members inserting pet projects into federal spending plans.
The bill was defeated by a large margin but this played into McCain's hands, allowing him to protest that Congress is wedded to pork-barrel politics.
He also gets high marks for his 'apple pie' home life: no scandals have muddied his marriage to the presentable and attractive Cindy. The couple have three children, one of whom has served in Iraq.
It all adds up to a presidential hopeful who many Americans, particularly the all-important swing voters, would be happy with.
Polls show him tied with Clinton in a presidential race, and only a few points behind if the contest is with Obama.
By contrast, the Democratic nomination race gets ever dirtier.
With few real policy differences, Clinton and Obama have become focused on taking swipes at each others' character.
The once squeaky-clean Obama is under fire for his relationships with a landlord now being tried for fraud, and with a Chicago priest who has been outed for a number of racist remarks.
Clinton, meanwhile, is facing increasing pressure to declare her tax returns and make public papers from the time when she shared an office in the White House with husband Bill.
Obama's foreign policy adviser Samantha Power resigned after calling Clinton "a monster" in The Scotsman.
Then last week Clinton fundraiser Geraldine Ferraro quit after saying Obama's success was down to the fact that he is black.
The problem with all this is that it dents the credibility of both candidates, and makes their party look foolish. But despite the urgings for an early end to the race by Democratic Party chairman Howard Dean, they are in for a long fight.
This is because Clinton's only realistic chance of catching up Obama's delegate lead lies in getting Florida and Michigan to re-run their primary votes.
Originally, their elections were declared void because both states brought forward their primary dates without permission.
