Bush described Bremer as a "can do" type
President George W Bush has appointed former US state department official Paul Bremer as the top civil administrator in Iraq.
Mr Bremer, 61, will oversee the transition to democracy, and will also have authority over Jay Garner, the retired general currently in charge of reconstruction efforts who reports to the Pentagon.
Mr Bremer's first job will be the highly contentious task of having to select a new Iraqi interim administration.
The Ambassador [Bremer] goes with the full blessings of this administration and the full confidence of all of us... that he can get the job done.
US President George W Bush
His appointment is said to have been designed to resolve bitter infighting between the Pentagon and the US state department over who controls the future of Iraq.
Correspondents say that Secretary of State Colin Powell is known to have been unhappy for some time over the Pentagon's dominant role in post-war Iraq.
Although Mr Bremer will still report to the Pentagon, his appointment is being seen as a victory for the State Department.
Described as a hard-headed conservative who commands the respect of all sides in Washington, Mr Bremer - also known as Gerry - is the former head of counter-terrorism at the state department.
Former assistant to six secretaries of state
1983-1986: US ambassador to the Netherlands
1986-1989: Ambassador-at-large for counter-terrorism
1989: Joins consulting firm Kissinger Associates
2001: Becomes chairman and CEO of the Crisis Consulting Practice of Marsh Inc
Most recently he has been running a consulting firm advising on risk management around the world.
Announcing the appointment, President Bush said he was "a person who knows how to get things done".
"He's a can-do type person. The Ambassador goes with the full blessings of this administration and the full confidence of all of us in this administration that he can get the job done."
The state department - which has radically different ideas for who should rule Iraq to the Pentagon - reportedly felt that as a military man, Jay Garner was the wrong person for the delicate task of selecting Iraq's future transitional rulers.
Colin Powell has consistently argued that the task of winning peace should be supervised by civilians and that many of America's allies feel the same way.
The BBC's Jon Leyne in Washington says the choice of Mr Bremer was clearly an attempt to broker a truce between the state and defence departments.
Although he is a career diplomat, Mr Bremer is also known as someone close to the Defence Secretary, Donald Rumsfeld.