Intelligence officials have confirmed the US has stopped searching for weapons of mass destruction in Iraq.
Duelfer confirmed in October there were no WMD stockpiles in Iraq
They say the chief US investigator, Charles Duelfer, is not planning to return to the country.
Mr Duelfer reported last year that Iraq had no stockpiles of chemical or biological weapons at the time of the US-led invasion nearly two years ago.
The existence of WMD had been the stated reason in Washington and London for going to war with Iraq.
Mr Duelfer said when he released his interim report in October that former Iraqi leader Saddam Hussein had still had the desire to restart WMD programmes.
IRAQ SURVEY GROUP
Set up in May 2003
First leader, David Kay, quit in Jan 2004 stating WMD would not be found in Iraq
New head, Charles Duelfer appointed by CIA
1,200 experts from the US, Britain and Australia
HQ in Washington, offices in Baghdad and Qatar
He will make a few adjustments to his report but he will close the book on the hunt when the final version is published in a few weeks, says the BBC's Nick Childs in Washington.
Officials are still sifting through a mountain of documents and say they will follow any leads they find but there is no expectation that the hunt will be revived.
The Iraq Survey Group (ISG), which was responsible for the search, continues its work but with the focus now on trying to help counter the Iraqi insurgency.
White House spokesman Scott McClellan said Wednesday's announcement was nothing new and that Mr Bush had referred to the end of the search last year when Mr Duelfer's interim report came out.
But a report earlier on Wednesday in the Washington Post newspaper stating the search was over led to what appeared to be a confirmation by the spokesman.
Asked if the ISG had stopped actively searching for WMD, Mr McClellan said: "That's my understanding... A lot of their mission is focused elsewhere now."
Former US inspector David Kay told the BBC's Radio 4 PM programme this was the expected outcome:
"You cannot believe how hard it is to motivate people in the field who know that all they are doing is going through busy work motions because they themselves know there are no weapons there.
"I faced that over a year ago with a team that essentially knew that we were right when we said they were no weapons."
He said the ISG's document search would now focus on the continued insurgency in Iraq and the money flow issue surrounding the oil-for-food programme.
Former head of UN weapons inspections Hans Blix also said there was no surprise in the announcement.
"We have believed that there weren't any weapons since around May or June 2003. First came David Kay in September 2003 [who said] that he hadn't found any weapons and that was a big sensation - but he thought that there were programmes still," he told the BBC.
"But then came Duelfer last November [who] said that he hadn't seen any programmes, but maybe Saddam would have intended to restart the programme, and there is no evidence of that.
Mr Blix said he assumed it would be natural for the United States to now report their finding to the UN Security Council "because the US took the inspections out of the hands of the UN to undertake it themselves".