Is George W. Bush a one-off phenomenon, so different from his likely successors that his presidency will be seen as an aberrant episode in US politics?

For the five years since the September 11 attacks, the event by which Bush chose to define his presidency, that has been the question the rest of the world has wanted to answer.

After these elections, it is tempting to say “Yes”. But although the Democrat revival will take the abrasive edges off the face that the US presents to the world, it would be a mistake to think that the US has taken a big step to the left.

In one sense, it is comic to ask whether Bush is a one-off; he is, after all, the son of another president. In replacing Donald Rumsfeld as Secretary of Defence with Robert Gates, he has brought in yet another of his father’s old advisers to try to resolve his predicament.

But when Bush defined his mission as winning the “War on Terror”, a fight against radical Islam, he fashioned a presidency entirely different from his father’s. He took the US into war in Iraq with little international support; he argued for government in which Congress and the courts would support the executive, not block it. The clearest message on Tuesday was that Americans have rejected Bush’s claim that the extreme new threat justified new powers for the presidency. They have forced him, for the next two years, to work with Congress; that is likely to persist whether his successor is Democratic or Republican.

They have also rejected his handling of the Iraq war, appalled at the damage to America’s reputation. The US is not likely, under Bush or his successor, to rush into another war — including in Iran. The US is also now likely to soften its high-handed tone towards other countries and the United Nations, although Condoleezza Rice, the Secretary of State, was trying that already.

Up to a point, Americans have also turned their backs on Bush’s brand of conservatism. Voters clearly rejected the White House’s tactics of playing to the base of committed conservatives and the religious right. The “centre struck back”, as one commentator put it.

But it would be wrong to portray these elections as the start of a new liberal era. The centre of US politics is still conservative in its reflexes, certainly by European standards. About half of the new Democrats in the House of Representatives call themselves part of the New Democrat Coalition, a centrist group, strong on national security questions. Others have signed up as “Blue Dog” Democrats, more rural and conservative in their instincts on abortion, religion, and same-sex marriage, and more prudent on government finances. Democratic analysts attribute some of Tuesday’s success to their organisation of the “religious left” as a political force.

There will be a distinct change on domestic policy — more talk about raising the minimum wage, and healthcare, and more interest from both parties in curbing deficits. But abroad? Other governments, dreaming that the US will now be conciliatory and co-operative, may be disappointed.

On greenhouse gases, where the US is regularly pilloried as a world villain, no politician is going to recommend a rise in taxes when the cost of petrol was one of voters’ biggest gripes. Common ground between many Republicans and Democrats also includes resistance to immigration and a suspicion of free trade deals.

Even where Democratic leaders would now like a change in policy, they are up against the same problems. They may urge a phased withdrawal from Iraq — but must then swallow the risk of soaring violence.

Elsewhere in the region, should they still try to promote democracy as the answer to militant Islam? The alternative — sticking by unpleasant, autocratic regimes — risks exchanging a strategy shaped too much by ideology for one devoid of it.

The features that the world has found infuriating about the Bush Administration will no doubt be softened. But that does not imply a huge shift in policy, under Bush or his successor. The centre of gravity of US politics would not support it — nor would the reality in Iraq.

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