He is supposed to be the most powerful man in the world with a full 50 weeks left in office. Yet, this year, George W. Bush has appeared more like the invisible man to one political party in the United States and a Guy to be tossed on the bonfire by the other.

Early last month Mr Bush left for a long trip to the Middle East, but because his flight coincided with the New Hampshire primary it was treated as an afterthought by the American media. A week ago he delivered the State of the Union Address, normally a highlight of the Washington calendar, but it was viewed as a modest news event to fill in the time between the South Carolina primary for the Democrats and the Florida primary for the Republicans.

The President will today send a massive budget over to Congress, where it will be put to one side by people more interested in the outcome of tomorrow's Super Tuesday showdowns. The United States has seen many a lame duck President. A lame dodo is more unusual.

It has been a long time since the man in the White House has seemed to cast such a small shadow on the battle to be his successor. In so far as the Democrats speak of Mr Bush at all, it is to dismiss all that he has done and promise sweeping change once he is out of the Oval Office.

Nor are the main Republican contenders bothering to mount a defence of their notional leader and his Administration. They are, in effect, stealing from Nicolas Sarkozy's strategy in France last year, when he overcame the liability of association with an unpopular Centre-Right President seeing out his second term by simply ignoring him, seizing control of the party that was once the property of Jacques Chirac, and then exploiting public uncertainties about a female rival long involved in a relationship with another prominent politician. This has to be the route by which John McCain, too, can retain the presidency for his party (whether he will celebrate by meeting and then marrying a glamorous model turned singer is more doubtful).

In a sense, the marginalisation of Mr Bush is not surprising. It is an extreme version of what has happened to everyone who has held his position into an eighth year. He has been living proof of the curse of the second term. In fact, the record of those who hang on for a second helping at the White House is so depressing that it might be a shrewd move for Mr McCain to exploit his age as an excuse not to seek one if he wins office.

At least Mr Bush has not been forced to resign in the manner of Richard Nixon, or faced impeachment votes in Congress over his sex life as did Bill Clinton. Apart from that, however, he has endured a brutal experience. For almost three years his approval ratings have been stuck at 30 to 35 per cent. His standing was symbolised by the mid-term elections of 2006, when the Democrats won control of the House of Representatives and the Senate, an event last witnessed in 1918 when Woodrow Wilson was the doomed President.

It was the mid-term defeat that convinced the Democrats that they would win this year and which persuaded Republicans that they had to distance themselves from the Bush era.

Yet, despite this, Mr Bush might end up having the last laugh.

First, while he may seem invisible, he is far from inconsequential. The tone of the fight in November will be set by the state of the economy and the success or not of American foreign policy. The President has sent an economic stimulus package to Congress that - out of fear of recession - has been better received on Capitol Hill than his approval levels might suggest.

It will be Mr Bush, not the various presidential aspirants, who decides what the United States will say and do about the international hotspots of Iran, North Korea and Pakistan. If the Republican Party calculates, somewhat harshly, that it owes him nothing, then he can reciprocate the sentiment. He will influence this election.

Secondly, although it has won him few plaudits with the electors, Mr Bush has had a decent run in Washington ever since the Democrats assumed command of Congress. They sought to impose a timetable for the withdrawal of American troops from Iraq and not only failed in this but have seemed slightly foolish since it became obvious that the controversial “surge” in that country has reaped real rewards in security. His foes then attempted to increase federal spending in their favoured spheres, but had to retreat in the face of presidential vetoes that they did not have the votes to challenge. The result is that the Democratic Congress is now much more unpopular than the President.

Finally, while the rhetoric around this presidential election may be about “change”, Mr Bush has most reason to know that continuity will be the outcome. His most important contribution to economic policy at home has been vast tax cuts that are due to expire in 2010. Those who would wear his mantle next are arguing about the form in which they should be renewed - the balance of benefit between the wealthy and the rest - but it has been conceded that they should be continued.

The President's other domestic legacy has been a huge expansion of spending on national and homeland security which, again, will be recast around the edges but will nevertheless remain intact for decades. In foreign affairs, neither a President Hillary Clinton nor a President Barack Obama would desert Iraq when the corner has been turned. They might rebrand the War on Terror but would not dare to abandon it.

As Super Tuesday looms, therefore, it is less invisibility than irony that is apparent. This election is indeed about “change”, but of a face, not the form that will come after.

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