Finally George W Bush is rewriting history, or at least history as he understands it. Until now his Mesopotamian adventure has been the new century's version of the struggle against Nazism and Communism, a noble and vital enterprise forced upon a wounded America. Now however a darker ghost is officially present, as the feast of hubris has turned into nemesis in Iraq. It is the shade of Vietnam. "It could be right," the President admitted this week, that the current upsurge in violence is similar to the Tet Offensive of January 1968, that in retrospect spelt the beginning of the end of the Vietnam war.
The Tigris of course is not the Mekong. As Tom Friedman - the New York Times columnist who this week first drew the parallel - points out, Tet was a co-ordinated offensive launched by the North Vietnamese and the Viet Cong against US and South Vietnamese forces. The daily slaughter in Iraq is far more complex. Only in part is it an insurgency against foreign occupiers, that threatens to make October 2006 the bloodiest month for US troops in almost two years.
Far deadlier is the toll being taken by the sectarian conflict between Shias and Sunnis. The heightened violence may be linked to the holy month of Ramadan. It may be geared to America's approaching mid-term elections, as US commanders in Baghdad claimed yesterday. Equally possible, however, it may be obeying an uncontrollable internal dynamic of its own.
But the similarities are at least as powerful. Tet brought home to ordinary Americans the futile and bloody nature of the war. Though the North and the Viet Cong suffered military defeat, they had scored a massive psychological victory. It occurred at the start of an election year that would become the most traumatic and convulsive year in modern US history. A fortnight before America elects a new Congress, there is a whiff of tumult in the air.
In this campaign, nothing matters like Iraq. Not the corruption scandals that have already sent two Republican members to prison; nor the sex scandal that has forced the resignation of the gay Florida Congressman Mark Foley; nor the embarrassment of the book by a former Bush aide showing how White House aides privately sneered at Christian conservatives, the most committed supporters of the Republican party.
Iraq has turned the usual dynamics of an American election on its head. For once Republican candidates are running from a national security issue. Talk about anything - but Don't Mention the War. Democrats on the other hand, who normally venture onto military terrain as if they were picking up a scorpion by the tail, are raising Iraq in speeches and ads across the country.
The Republican dilemma may be gauged by the President's travel schedule during the mid-terms. Bush likes campaigning, and is pretty good at it. At the last mid-terms in 2002, when his approval rating was 65 per cent or more, a personal appearance could tip the scales for a Republican in a close race. This time around, he is doing a lot of closed-door fundraising. But on the stump he is well-nigh invisible. For what individual candidate fighting for his political life wants to be seen with a President whose popularity is falling by the day?
And as Iraq worsens, so do the Republicans' overall prospects for 7 November. A few weeks ago, it was a toss-up whether Democrats would capture the net 15 extra seats they need to win control of the House of Representatives. Now the talk is of a net swing of 25 or 30 House seats - and of a possible Democratic capture of the Senate as well.
But what is to be done? If there were an obvious pre-electoral change of course in Iraq, Bush would leap at it. So, needless to say, would the America people, two thirds of which now believe the war was a mistake. But the harsh truth is that no good option exists. General Sir Richard Dannatt is absolutely correct when he says that the presence of foreign troops only exacerbates the situation in Iraq.
On the other hand, the large US force on the ground is the only thing preventing Shias and Sunnis sending their own armies into the field, and transforming a low-level civil war into the real, all-out thing. From a strictly military viewpoint, there is at least as strong a case for boosting US troop strength in Iraq as there is for cutting it back.
Parse Mr Bush's ever-shaky grammar if you are so inclined. Maybe his increased emphasis of "flexibility" in Iraq does presage a dramatic new policy departure, an "October Surprise" for 2006. Perhaps his repeated promises that he will do what the generals on the ground want indicate a readiness for change. But don't bet on it.
Realistically, the best opportunity for a policy overhaul lies beyond the election, when the Iraq Study Group, a bi-partisan commission of the great and the good, headed by James Baker, Secretary of State under Bush the elder, presents its conclusions, probably in December or January. Baker's closeness and loyalty to the Bush family is legendary. But he has already said that some of the group's recommendations will not be to the liking of the White House - including, it appears, a suggestion that the US enter talks with Iran and Syria on the future of Iraq.
Iraq's President, Jalal Talibani, has declared that this would spell the beginning of the end of the violence within months. However, Mr Bush has built his Presidency on the principle that you don't talk to the bad guys. Is such a reversal really conceivable - and at the very moment the US is leading the charge for UN sanctions over Tehran's nuclear ambitions?
Ditto, the other long aired possibility, the removal of Donald Rumsfeld from the Pentagon. The odds remain that Rumsfeld, the longest serving Defense Secretary since Robert McNamara, will be gone by the end of the year or soon thereafter. Like McNamara before he announced his resignation in November 1967 (two months, incidentally, before the Tet Offensive), Rumsfeld has become the symbol and increasingly the scapegoat for an unpopular war. Nothing would signal change in Iraq as clearly as a change at the Pentagon.
But the eternal problem remains: for Bush, the removal of his Defense Secretary, with whom he has stuck through thick, thin and even Abu Ghraib, would be a neon-lit acknowledgement that his war has been a mistake. And this President, as we know, hates nothing more than to admit error.
But war is creating its own political reality, that could turn such squeamishness into a mere footnote to history. Just as the Tet Offensive of that long-ago January, the unrelenting bloodshed in Iraq could herald political turbulence at home, of which the mid-terms are only the start.