Tony Blair said it himself - attempting to offer a bridge between the US and Europe was often more like walking a "damn high wire".
By Nick Assinder
Political Correspondent, BBC News website
Even as he spoke, and as if to prove the point, French President Jacques Chirac was giving the prime minister's tightrope a good shaking.
Mr Chirac has different world view
In a blunt-speaking interview with British journalists before his two-day visit to the UK, Mr Chirac warned Mr Blair he was wasting his time with President Bush.
The prime minister had given the president support in the war on Iraq and received nothing in return.
"I'm not sure it is in the nature of our American friends at the moment to return favours systematically.
"I am not sure, with America as it is these days, that it would be easy for someone, even the British, to be an honest broker," he declared.
Probably worse for the prime minister, however, was the French president's support for a "multipolar" world in which Europe would offer a balance to the US.
That flies absolutely counter to both Mr Blair's and Mr Bush's world view - not to mention the vision of the so-called neo-Conservatives in Washington.
It suggests a far more serious and fundamental clash of rival visions for the world that cannot be squared, rather than a simple falling out over a single issue.
Ms Rice is close to Bush
Mr Chirac's comments came on the day Mr Blair was delivering his big annual foreign policy speech and attempting, once again, to offer himself as that bridge between Europe and the US.
He urged the White House to do more to reach out to the EU in the wake of the divisions over the Iraq war.
His call came amid fears amongst some on the Labour benches over the likely political direction of the White House following the resignation of chief moderate Colin Powell and his reported replacement by the hawkish Condoleezza Rice.
The prime minister tied his plea to President Bush with an equal call on European leaders and others to stop ridiculing US arguments and parodying its leaders.
Mr Chirac, however, had just described hardline US Defence Secretary Donald Rumsfeld - who once dismissed his regime as part of "old" Europe - as "that nice guy in America, what's his name again?"
There are now real fears in Westminster that the French President may repeat his views during his visit to Britain later this week.
Mr Chirac is at odds with Mr Blair
The two leaders will hold a summit and host a joint press conference during the trip.
And that may well serve to focus attention onto the continuing splits between the EU on one hand and the UK and US on the other.
Mr Blair's speech had been partly designed to dispel the image of him constantly standing alongside the US in opposition to the EU.
Mr Chirac's comments have made his task more difficult by suggesting it is time the prime minister paid more attention to his European alliances.
That is a view held by many of the prime minister's critics at home, notably backbenchers led by the likes of former Foreign Secretary Robin Cook.
They believe it is high time Mr Blair stopped trying to walk his high wire and started rebuilding bridges with Europe before he falls off and hurts himself.