President Bush was put on notice yesterday that he has until October to announce a withdrawal plan from Iraq before the bulk of the Republican Party deserts him.

Two of the party’s most respected and influential figures, Senators John Warner and Richard Lugar, said that Iraq’s divided Government was unlikely to make any political progress this year and that Mr Bush had to start planning a change of course now. The senators, the party’s leading authorities on military issues, have proposed legislation requiring Mr Bush to give a plan to Congress by October 16 that would seek a withdrawal of combat troops starting as early as January 1.

Their amendment, which does not set a firm deadline, is likely to become the main Republican alternative to Democrat demands for a complete and timetabled withdrawal.

If the report to Congress in September by General David Petraeus, the US ground commander, fails to show that Mr Bush’s surge strategy is making significant progress, the Warner-Lugar option will give political cover to a potentially critical number of Republican senators to desert Mr Bush.

The President halted the Republican revolt successfully last week and has in essence got two more months – until General Petraeus’s report on September 15 – to show that the surge is working. Senators Warner and Lugar have paved the way for Republican defections after September, without the need to side with Democrat demands for a complete US withdrawal by April. “The Baghdad Government is not likely to perform as we had hoped so the President will have to make changes,” Mr Warner said. His plan seeks a withdrawal of US combat troops, with enough remaining to train Iraqi forces and fight al-Qaeda. Mr Lugar said: “What we are looking for now is a plan that is much more realistic for the use of our troops in Iraq.”

Votes in both the House and Senate last week made clear that despite his low approval ratings and deep public dismay over the war, Mr Bush has managed to keep enough Republicans on side to keep antiwar legislation from progressing on Capitol Hill – but that could change after September. A Newsweek poll yesterday found that 64 per cent of Americans believe the surge has failed.

Stephen Hadley, Mr Bush’s National Security Adviser, rejected the Warner-Lugar plan as premature. “They’ve done a useful service in indicating the kinds of things that we should be thinking about. But the time to begin that process is September.”

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