Speaking in Ohio, Mr Bush urged politicians to not pursue a withdrawal now, urging patience until the head of US forces in Iraq reports in September.

Gen David Petraeus, who will make that report, has stressed that the extra troops have only just arrived.

Last week senators from Mr Bush's party joined opposition calls for a pull-out.

"I fully understand how tough the war is on the American psyche," Mr Bush said.

"And I know people are looking at their TVs and asking if it is worth it," he added.

"Yes it is," he insisted, saying that the conflict was vital to deny al-Qaeda a safe haven and ensure the safety of the American people's children and grandchildren.

Mr Bush asked the US to look beyond this week's upcoming status report on Iraq - an assessment of Iraqi progress toward meeting political and military objectives, which will be delivered to Congress on Thursday or Friday.

"I believe that it is in this nation's interests to give the commander a chance to fully implement his operations and I believe Congress ought to wait for General Petraeus to come back and give his assessment of the strategy that he is putting in place before they make any decisions," Mr Bush said.

"That's what the American people expect. They expect for military people to come back and tell us how the military operations are going."