President George W. Bush has said Congress must wait until September before it receives the US military’s assessments of whether the 30,000 troop surge to Iraq is working. But a growing number of Mr Bush’s Republican colleagues have already reached their own conclusions.

On Monday, Richard Lugar, the senator for Indiana and normally a Bush loyalist, said that “the costs of continuing down the current path [in Iraq] outweigh the potential benefits that might be achieved”.