A new blueprint by Senators Richard Lugar and John Warner was similar to plans from anti-war Democrats to yank soldiers out of the cauldron, with an important difference -- it did not include a hard date for troop withdrawals to be completed.

Lugar and Warner released their plan Friday, a day after Bush rejected any changes to the war plan until US commander in Iraq General David Petraeus gives a definitive report on his troop "surge" strategy within two months.

"We are attempting to ensure that US military and diplomatic policy is prepared for change when the Petraeus report arrives in September," Lugar said.

"We are hopeful that regardless of where senators stand on surge versus withdrawal, they will find our amendment to be a constructive bipartisan attempt to prepare for whatever policy follows in the coming months."

The plan also calls on Congress to reauthorise Bush to conduct military operations in Iraq, and to replace the 2002 authority he was granted by lawmakers, which became the basis of the invasion in 2003.

Bush vowed to stick to his current course in Iraq on Thursday after a keenly awaited interim report on the surge showed only meagre progress by the Iraqi government on a set of benchmarks for military and political progress.

The Lugar-Warner amendment, which appears designed to unite those Republicans who have broken with Bush on the war with anti-war Democrats, calls for a new plan narrowing the mission of US troops in Iraq to be delivered to Congress by October 16.

The president should be ready to start carrying out the new approach by the end of the year, the amendment to a defence policy bill currently being debate in the Senate said.

It called for US troops to be transitioned from "policing the civil strife or sectarian violence in Iraq" and their redeployment as "conditions permit."