There are many sensible reasons for Tony Blair not to intervene in America's presidential election. He will want to be the very best of friends with the winner on the day after the vote - but he cannot know who that will be. Few in Whitehall have forgotten the Major government's blunder in helping the Republicans dig for dirt on Bill Clinton, and President Clinton never forgot it either. Though the working assumption has been that George W Bush will be re-elected, seeming to back him over John Kerry may yet prove, come November, as much of a mistake as John Major's over Clinton.
But the real preference for Labour people in this election does not depend on the polls. Political values cross national boundaries. Every member of the Labour Party always wants a Democrat to beat a Republican. And we especially want this Democrat to beat this Republican. The same is true of most Labour ministers, and we all hope that includes the Prime Minister. True, Bush's defeat, following Jose MarIa Aznar's defeat in Spain, would add to the pressure on Blair over Iraq. But the gains would be greater. British pressure for a multilateral approach to postwar Iraq and to the Middle East would be far more effective if applied to a US administration that itself believed in a multilateral approach.
Senior Labour MPs and ministers can admit this preference privately but ministers must stick to the script in public: that the American election is a matter for the American people, and that British ministers would not dream of intervening.
Does this make sense? Blair's central political belief is that domestic and international politics cannot be separated. He seems to regard the conventional doctrine of electoral non-interference as rather 20th century. One of his foreign policy gurus, Robert Cooper, who is credited with much influence in shaping Blair's interventionist doctrines, once suggested that every EU citizen should have two votes - one for their own national election and one to cast in an election of their choice elsewhere in the EU. Blair seems to have taken this to heart and has made a fairly regular habit of interfering in other people's elections, swinging by to campaign for Gerhard Schroder in Germany or to make a speech in Stockholm in the final days of the ill-fated Swedish euro campaign. To the chagrin of the victorious Socialists, Downing Street scarcely disguised its support for the right in the recent Spanish elections.
The US elections will do much more to shape the global politics of the next decade than any of our local European spats. And in not choosing, we choose. Blair can't help but intervene in the US election anyway. Trying to keep out of it makes him, by default, part of the Bush-Cheney re-election campaign: after all, the Republicans have precious little videotape of other prominent foreign leaders standing shoulder-to-shoulder with their man. To be truly neutral, Blair would need to get himself pictured with Kerry after the senator is formally anointed at this month's Democratic Convention. Moreover, Blair's closeness to the administration has already made Britain a voice in America's internal debates - between Colin Powell and Donald Rumsfeld, the State Department and the Pentagon.
Even if the government must maintain a formal neutrality, the Labour Party need not. It could invite Kerry, as the leading progressive hope for international leadership, to give a foreign policy speech as guest of honour at the annual conference.
But those of us who want to see Kerry win should not overstate the difference between a second Bush term and a Kerry presidency. Kerry's foreign policy thinking - and his team - are still in formation. He seems tempted to paint himself as a conventional foreign policy "realist" against the Wilsonian idealism of the Bush team - and he would have to govern with a Republican Congress. But if Kerry were, by instinct, to be rooted firmly in the postwar US foreign policy mainstream, a second Bush administration would itself probably be more conventional: the timetable for grand neoconservative visions of democratising the Middle East has, at the very least, been set back by the realities of postwar Iraq.
The most important differences might be in tone as much as substance. Tone matters. The gravest indictment against the Bush presidency on the campaign trail should be how the immense levels of goodwill that existed around the world towards the US on 12 September 2001 - "we are all Americans now", as Le Monde put it - have been squandered. We shall never know if a President Al Gore would have prosecuted a "war on terror" differently by using US leadership to shape the more effective multilateral regime that the world needs. But under Bush, America's "soft power" - the worldwide appeal of its open society, symbolised by the Statue of Liberty and the commitment to democracy and human rights - has been badly damaged. US policy-makers should worry that, even in Europe, the votes are in opposing the US, while allies such as Blair risk paying a high political price. That Osama Bin Laden's trust ratings in Egypt are higher than Bush's puts any US aspiration for Middle East democratisation in stark perspective.
If Kerry were elected, there would be an enormous sigh of relief around the world. But what would happen next? While America's calamitous public diplomacy makes a fresh start important, getting rid of Bush would hardly solve all the world's problems. Finding a more effective way to respond to crises and failed states will be considerably more difficult than mocking the arrogance and hubris of Rumsfeld. Kerry would surely ask whether the Europeans can find the cohesion and capacity to make our foreign policy aspirations any more than rhetorical.
The debate on intervention will not go away. The international left moved a long way in the 1990s in response to Bosnia, Rwanda and Kosovo. Some argue that Iraq was the natural culmination of this growing support for "humanitarian intervention", others that the war (based on pre-emption and those elusive WMDs) did not fit the model at all. But as Martin Woollacott - hardly a neo-con hawk - wrote recently in his final Guardian column: "Iraq muddled and muddied a decade of argument about right action, but that does not mean that the argument should be abandoned."
The global schism over Iraq has set back still further the elusive hope of United Nations reform, and undermined the "Responsibility to Protect" agenda championed by the UN secretary- general, Kofi Annan. The deep tension right at the heart of the UN Charter - which declares both the universal human rights of people and the sovereignty of the states in which they live - is likely to be with us for many decades yet.
To expect a Kerry presidency to resolve these issues would be to set hopes too high. The more likely outcome of a Kerry presidency will be a return to some of the foreign policy frustrations that US allies experienced in the Clinton years, but in a new, post-9/11 context. Yet that would be a considerable advance on where we are now.
The world will watch the US elections anxiously, but only Americans will have a vote. The danger is that global opposition to Bush could bolster his appeal at home - unless there is an opposition voice that clearly rejects a virulent anti-Americanism and appeals to the other and better America. That is the role that could be played by Blair - the international figure to whom US voters are most likely to listen. In an election that could again come down to hanging chads in Florida, he could make a decisive difference.
Sunder Katwala is general secretary of the Fabian Society (email@example.com)