He knows that some of the families will not want to see him, and he understands. Grief works in different ways, he says. For others, however, it will be an opportunity to talk, to learn something, he hopes, of the inexplicable nature of their children's deaths.

So, when he has a moment, when he is not driving round the battlefield that is eastern Baghdad, Vail examines the map and plans his flights and his car hire. And he wonders at the reception he will receive - a messenger of death, bringing the war back from Iraq to the home front.

For when Vail and his soldiers return, it will be in the knowledge that the United States that they are going home to is not the one that they left. That in their year-long absence a seismic shift has occurred in support for the war in Iraq. And that the deaths that Colonel Vail must carry back with him to grieving families - deaths that once seemed to Americans to be a necessary cost - now seem to the majority a dreadful and pointless waste.

It will also be in the knowledge that the battle that they began with such confidence barely four months ago, to secure and then rebuild some of the most dangerous areas of the Iraqi capital, like the campaigns before, has failed.

With that failure the entire future of Iraq and the US and British-led occupation has been brought to a tipping point of enormous consequence not simply for Iraq and the region, but for the Bush and Blair administrations.

For despite a massive campaign involving the troops of Vail's unit and others, backed by thousands of Iraqi troops, the US military leadership in Baghdad has been forced to admit that attacks during the holy month of Ramadan have increased by 22 per cent, and that the US death toll for October, standing at 74 at the weekend, will be one of the deadliest for US troops since the invasion in 2003.

More worrying still is the assessment that both Sunni and Shia nationalist resistance movements have reached the level of being 'coordinated/consolidated' - able to reply to multinational offensives with their own 'push capability'.

This was admitted explicitly last week by the top US spokesman in Baghdad, General William Caldwell. 'We're finding insurgent elements, the extremists, are pushing back hard. They're trying to get back into those areas where Iraqi and US forces have targeted them,' he said. 'We're constantly going back in to do clearing operations.'

In a few short weeks, the US and British policy over Iraq has dramatically unravelled. In the US that policy has been summed up in the phrase 'stay the course', the message designed months ago by Republican strategist Karl Rove, as a stick with which to beat the Democrats in the critical midterm elections on 7 November. It was a simple formula intended to suggest that it was President Bush, and not those calling for a rethinking of the war, who was the patriot.

Now that message appears to be backfiring as many Republican candidates up for re-election on 7 November have sought to distance themselves from Bush's handling of the war.

It is an unravelling driven by the increasingly dire circumstances on the ground, which have seen a sharp escalation of the blood-letting as the government of Prime Minister Nouri al-Maliki weakens in the face of the challenge of the Shia militias.

It has been driven, too, by the criticisms voiced by senior military figures - both American and British - of the conduct of the war, and it has been accelerated by the most potent catalyst of all, the collapse in popular support for the handling of events in Iraq, most notably in the US. Recent polls have suggested that disapproval of Bush's handling of the war in Iraq is now hovering around 63-64 per cent.

The collapsing poll figures mean that suddenly it is not only the Democrats who are challenging the Bush administration's conduct of the war but Republican incumbents themselves, fearful that the White House's longstanding denial of the reality of the situation in Iraq will toss them out of power.

Republican strategists believe that in the House of Representatives 12 seats inevitably are doomed, with the Democrats needing only 15 seats to take the House. Privately, however, the same strategists concede that a loss of 18-25 seats is more likely. In the Senate, too, controlled by the Republicans for all but one of the last 12 years, the Republican hold is under threat.

The result has been a political fall-out that many now expect will pressure Bush - and by extension the UK - into yet another change of tactics over the conduct of the war. The question remaining is what policy could now deliver any more success?

That expectation of change has been driven by ever more visible criticism in the US media over a policy that many now believe is political poison.

It has not been helped by the comments of President Bush himself. He responded to an article by columnist Thomas Friedman which compared the present spike in violence in Iraq to the Tet offensive in the Vietnam War by appearing to accept the comparison.

'I don't believe that we can continue based on an open-ended, unconditional presence,' Senator Olympia Snowe, a centrist Maine Republican, told the Washington Post last week. 'I don't think there's any question about that, there will be a change.'

Snowe is not alone. Senator John Warner, the Republican chairman of the Senate Armed Services Committee, has also weighed into the fray after returning from a fact-finding mission to Iraq and stating, in sharp contradiction to Secretary of State Condoleezza Rice during her visit last month, that the country was adrift and all options should be examined.

Most damning of all, however, were the comments of Richard Haass, a former Bush administration foreign policy official, who told reporters yesterday that the situation is reaching a 'tipping point' both in Iraq and in US politics.

'More of essentially the same is going to be a policy that very few people are going to be able to support,' said Haass, now the president of the Council on Foreign Relations. He added that the administration's current strategy - of a stable, democratic Iraq, within a politically feasible time frame - 'has virtually no chance of succeeding'.

This sense of a growing crisis has only been deepened by comments from the Iraq Study Group, chaired by the Bush family friend and former Secretary of State James Baker, which have made it abundantly clear that he does not believe that the present Iraq policy is working.

In a second uncomfortable comparison with Vietnam and the Tet offensive, some are now beginning to compare Baker's bilateral group with the 'three wise men' who advocated the change of US military policy in that war.

Baker has let it be known to Bush that he believes that what is required is a timetable for withdrawal. But that comes with its own problems.

'Jim's problem is that he wants a way to make clear to Maliki that we're leaving, but without signalling to the Shia and the Sunni that, if they bide their time, they can battle it out for Iraq,' one long-time national security expert told Friday's New York Times. 'How do you do that? Got me.'

If there is an answer to that question, then Deborah Pryce would like to know - and in a hurry. A popular Ohio congresswoman, a moderate Republican, Pryce's only political error may turn out to have been in getting too close to her party's leadership during the execution of a highly unpopular and expensive foreign war.

In November, she will probably leave office as decisively as she arrived in the Republican midterm sweep in 1994. Pryce would like to talk about local issues like the new control tower at Columbus airport, but the country is in alarm over the war in Iraq, the faltering economy and political sleaze in Washington. For Pryce, the fourth-ranking Republican in Congress who has not faced a serious challenge since she was elected in 1994, her seat, in the 15th district, is a microcosm of the national picture. For, as a touchstone state, what is true for Ohio is true nationally.

In Ohio all the talk is of war and broken government. Incumbent Republicans in all races - House, Senate and governorship - are behind by double digits. In the Senate campaign alone, the Republican national committee has cut campaign spending on its amiable candidate, Mike DeWine , and reallocated campaign money to other states such as Tennessee where victory is still a possibility. While other issues come and go on the front pages, war is the constant, the backdrop.

Once candidates such as Pryce could count on the 'soccer mums' renamed 'security mums' for the post-9/11 world. Once these women accepted the administration's explanation for war. Not any more. 'People are upset about our kids being killed in Iraq in a war that everyone now knows was started on false pretences,' said housewife Vicky Harman. 'Every day there's more information about the cover-ups, the efforts to misguide the public and - worst of all - their absolute lack of remorse.'

With the realities of Iraq as a 'new Vietnam' setting in, voters in the Midwest last week expressed a sense of political powerlessness. Julie Smith wanted to see 'the boys come home from Iraq' but didn't expect them to 'cause I know Bush is gonna do what he likes'.

If there is a hope of wide-ranging change in large quarters of the Republican Party and in Washington's political circles at the week's end it was not being articulated by the two men most closely associated with the war, Bush himself, and his closest lieutenant, the combative Defence Secretary Donald Rumsfeld, whom many believe should be sacrificed for the errors of the war so far.

Ahead of a meeting with Vice-President Dick Cheney and the top American commanders in Iraq - George Casey and John Abizaid - Bush and Rumsfeld were still insisting that the goals remain unaltered: creating a country that can govern and defend itself 'that will be an ally in the war against these extremists'. By yesterday Bush was even more emphatic in his weekly radio address, insisting that, while the increase in violence was disappointing, 'our goal in Iraq is clear and unchanging: our goal is victory. What is changing are the tactics we use to achieve that goal.'

If anyone was left in any doubt, Secretary of State Condoleezza Rice also played down expectations of a major change when she briefed reporters while en route to Moscow. 'I would not read into this somehow that there is a full-scale push for a major re-evaluation (of Iraq strategy),' she said.

Perceptive analysts have noted, however, that while Bush has remained apparently robust, he has dropped his insistence that the end product of his policy is the creation of a 'flourishing democracy' at the heart of the Middle East to focus instead on the much more limited idea of a 'stable' Iraq. Now, the message from the White House and Pentagon is that, while tactics on the ground may be up for grabs, the overall strategy is not. None of which may be enough to save a Republican meltdown.

This considerable problem is being confronted by not only the disillusioned US electorate, but by Bush's allies as well. For it is not only in America that the implications of the unravelling of Bush's Iraq policy are being felt.

For if the situation is difficult for Bush, it is infinitely more complicated for his supposed ally, Tony Blair. Already wrongfooted by the outburst from the Chief of the General Staff , General Sir Richard Dannatt , Downing Street has spent the week struggling to stay on the right side of a constantly changing argument in Washington.

Foreign Secretary Margaret Beckett , who has spoken to Condoleezza Rice within the last few days, will indicate today that tactics were bound to change in the run-up to the US polls, but she insists that she does not detect 'that much of a change of pace or mood' in the Washington administration on Iraq. However, she admits there are ongoing discussions about the way forward: 'I think it is just people recognising how things are going and there are bound to be some areas where it would be easier if we were not there.' What was most striking, she said, was that 'in some areas we were part of the problem, in other areas we were not.'

The difficulty for the British government is that American policy on Iraq is now likely to be determined by the outcome of the November elections: if Bush does badly, an early exit becomes more likely, but if he does unexpectedly well there could even be a push to send more troops to Iraq to quell the insurgency.

As the junior partner in the coalition, Britain will inevitably be swept along by whatever new American policy emerges. But that policy remains unclear, leaving British politicians essentially playing for time until they establish what Bush is likely to do.

And Bush is not the only one with elections on his mind. If the midterm contest goes badly for the Republican Party, Labour minds will inevitably turn to the elections due here in May for local councils and the Scottish and Welsh assemblies. In Scotland particularly, Iraq is a hot political potato and Labour's two main opponents north of the border, the Liberal Democrats and the SNP, are both highly critical of the war.

All of which, however, is academic for those in the killing fields of Iraq.

Ending the Iraq nightmare - the key points

A Partition

What it means

One of the options being looked at by James Baker and his team - asked by Bush to study the exit alternatives. Lines would be drawn across a map of Iraq dividing it into three autonomous regions - Kurdish in the north, Sunni in the middle and Shia in the south.

Consequences

Dividing Iraq along sectarian lines would exacerbate sectarian violence and lead to ethnic cleansing. It would also unequally split up Iraq's oil resources - and leave the Sunnis with little arable land - which would give opposing sides an economic reason to fight each other. Partition would be far from straightforward in heavily mixed communities, holy cities would be contested and Baghdad would probably explode.

Support

Outside powers such as Iran would find it easy to dominate the new entities. The militias are already creating a partition and more and more people are becoming displaced.

B Regional help

What it means

Sub-contracting problem - asking Iran, Syria and Saudi Arabia to step in.

Consequences

Risks drawing the regional players into a wider conflict that could engulf the Arab world. It could mean Bush facing demands from countries he regards as enemies in exchange for help. It's also debatable whether any of those countries would have influence to curb sectarian killings.

Support

It looks good on paper, Baker is very keen, but not popular in Washington. White House press secretary Tony Snow said it unlikely Bush administration would consider ending its ban on talks with Iran and Syria. 'We'd be very happy for them not to foment terror,' Snow said. 'But it certainly doesn't change our diplomatic stance towards either.'

C Immediate withdrawal

What it means

The cut-and-run option where the US-led coalition troops simply pull out overnight.

Consequences

Could worsen the chaos and enfeeble the struggling Iraq government and military. Danger of full-scale civil war and carnage, destabilising the region and leaving a failed state open to use by al-Qaeda. But it would stop UK and US soldiers dying.

Support

Bush will never be persuaded it is the right thing to do. The aim has always been to leave an Iraq that could govern itself. It would mean utter humiliation for his war on terror. The US would forever be blamed for the mess it left behind and could even be forced to intervene again in the future. Bush has been listening to Henry Kissenger who has told him cut and run is not an option and 'victory is the only meaningful exit strategy'.

D Phased withdrawal

What it means

'We notify the Iraqis that we're going to be drawing down a reasonable but careful percentage of our troops over a reasonable interval of months - for example 5 per cent every three months,' said Richard L Armitage, former presidential adviser. US General George W Casey has suggested Iraqi security forces would be ready to take over in 12-18 months. Views of whether it takes weeks or years vary but the pressure is on Bush - and Tony Blair - to produce a timetable.

Consequences

If the weak Iraqi government makes no progress in disarming the militias and death squads then the same results as immediate withdrawal. Insurgents would perceive it as a victory and move into the vacuum.

Support

Democrats winning control of one of the Houses of Congress would increase pressure for an end date to be set. Favoured by Britain and the subject of the row earlier this month engulfing General Sir Richard Dannatt's comments when he called for a swift pull-out of UK troops. Blair has also stressed a desire to leave but only when 'the job is done.'

International press: what they are saying around the world

Los Angeles Times

Tim Rutten, yesterday

The Bush administration's problems in Iraq have nothing to do with public relations and everything to do with the facts. American voters - a substantial majority of whom now recognise the war in Iraq as a mistake - will make their own decisions in November, but the real lesson concerning the American failure in south east Asia that the news media ought to hold in mind over and against all criticism - no matter how adroitly it's spun - can be summed up in one word: quagmire.

New York Sun

Daniel Freedman

Iraq is not like Vietnam, as the anti-war movement likes to say - ie, a failure The reality is America only lost [in south east Asia] because the political leadership lost the resolve to back the troops The crucial part now is to ensure American troops aren't abandoned as in Vietnam.

El Pais

'Impossible Victory', yesterday

All the alternatives Bush has put on the table to solve an increasingly deteriorating situation in Iraq are terrible. This war - and above all its bad management, even more so than at the beginning of the war- has finally turned into the focus of the campaign for the American Congress elections on 7 November. Even the president has now recognised its resemblance to the Vietnam war.

At this stage, the Bush administration is looking for a political escapade. But if the option were clear, they would have already opted for one.

Le Monde

'The strategy in Iraq puts the Congress elections at stake', 18 October

Will James Baker succeed in finding an exit strategy in Iraq's dead end for president George Bush? Three weeks before the Congress elections that some observers see as the 'referendum on Iraq', the former Secretary of State is omnipresent in the media, accrediting the idea that the change of policies in Iraq is perhaps less distant, as opposed to Bush's denials of change.

Mr Baker promotes this idea specially in his book, an autobiography where he shares his emotions as well as revealing his discovery of African-American cousins and his taste for hunting, a pastime he shares with the father of the current president.

Sydney Morning Herald

Leader, yesterday

The debate over Iraq policy in the US, Britain and Australia is being driven by bad news from Baghdad and increasingly hostile public opinion at home. It is good that this is forcing political leaders to review and adjust their strategies. It will be even better if it leads them to stop reviling their critics as traitors or cowards and instead explain the moral, political and military complexities of the Iraq situation. The case against a premature withdrawal should not rest on defence of an invasion that was launched partly on false pretences but, rather, on the new realities created by that invasion and its bungled aftermath. So dire are those realities that pulling out now would not only expose the Iraqis to the danger of even worse bloodshed in an outright civil war, but also present violent jihadists with a victory that would embolden them to further atrocities.

Washington Post

Colbert King, yesterday

There is a new Iraq emerging before our eyes. It is an Iraq that torments Christians, that indulges in unrelenting sectarian bloodbaths, that cheers for Hizbollah, that is no more a friend to Israel than is Iran, all despite the lies sold to the White House and Pentagon by self-serving, power-hungry Iraqi expatriates. The new Iraq is not what George W. Bush talks about. But that's the Iraq he's got. And, worst of all, that's the Iraq we are in.'

The Economist, London

Leader, yesterday

The only honest alternative is indeed probably just to go and let one side win. America did that in Vietnam and Britain did it in Palestine ... Vietnam turned out well enough, regional dominoes did not all fall and America went on to win the cold war anyway ... Maybe something similar will happen in Iraq, not least because the rival versions of theocracy on offer from Iran and al-Qaeda are nonsensical too. But just going would be a fantastic gamble, not only with America's global power and prestige but also with other people's lives. Better, still, to stay.