President Bush has just three months to show that his troop surge strategy in Iraq is working if he wants to stop further erosion of what remains of Washington’s political will for continuing the war. Both supporters and critics are looking towards a red-letter date in September when General David Petraeus, the new US commander in Iraq, delivers his progress report on this year’s influx of about 30,000 additional American troops.

The White House is playing down the significance of General Petraeus’s assessment, with Tony Snow, the press secretary, insisting it is not “a pivotal moment” and should be seen merely as a “first opportunity” for examining progress. But Mr Bush himself last month referred to it as a “critical moment”.

Democrat leaders in Congress this week sent the President a letter declaring that the “escalation has failed to produce the intended results” in recent months, which had been marked by a rising tide of deaths and stumbling efforts for sectarian reconciliation.

In each of the past two months more than 100 US soldiers have died. The Democrats’ letter promised fresh legislation designed to “bring the war to a responsible end”.

Even more worrying for Mr Bush, patience is wearing out among Republicans who staved off an earlier effort to impose deadlines for troop withdrawals. Senator John Warner, a bellwether for the party, has stated that Mr Bush should change course even before General Petraeus’s report.

“The facts on the ground, if they continue to worsen as they have been here in the past months, would make July an opportune time,” he said.

Stephen Biddle, a senior fellow at the Council on Foreign Relations who recently returned from Iraq where he was advising General Petraeus, acknowledged yesterday that he felt “pessimistic” about the prospects of the surge plan. Although he cautioned against exact predictions, he said: “If I had to attach a number, I would say we have a one in ten chance of succeeding – but that does not mean we should pull out. It is a long-shot strategy to prevent the terrible consequences of a region-wide war in the next decade. I fear that political reality means we will probably eat those consequences eventually anyway.”

Mr Biddle expects to hear a “mixed message” from General Petraeus “which will disappoint those on both sides who are looking for something clearer”. While about one third of Baghdad is now under control, “that is not as good as we had hoped for”.

There are signs that Mr Bush may already be preparing a fall-back option, favoured by moderate Democrats and Republicans, of withdrawing up to half the current 150,000 US troops and moving those remaining into training or support roles. This was advocated by the report last December from the independent Iraq Study Group.

The president has in recent weeks adopted noticeably warmer language towards the proposals than when he announced the surge strategy earlier this year. Some observers are saying that there is not a “plan B” but a “plan B-H” – a reference to the study group’s co-chairmen, James Baker and Lee Hamilton.

Robert Gates, the Defence Secretary and a former member of the Baker-Hamilton group, has suggested Congress needs to reach a consensus on how many troops are needed to stop a broader regional war and terror attacks on America. “Whether that’s 25,000 troops or what the number is – I have no idea,” he said.

The recent departures of General Peter Pace from the post of Chairman of the Joint Chiefs of Staff and that of JD Crouch as Mr Bush’s Deputy National Security Adviser – both closely linked to existing policies in Iraq – are being seen as possibly preparing the way for a new direction.

So, too, is the arrival of Gen Douglas Lute as the Administration’s new war “czar”, because he had previously been sceptical about the surge having anything more than “temporary, localised effects”.

Mr Biddle said: “The great majority of Congress wants a middle way that allows them to reduce troop numbers without admitting defeat. The trouble is that would be lousy military strategy.”

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