New US director of national intelligence Mr John Negroponte faces battles within the intelligence community, according to analysts.
Mr Negroponte, currently the US ambassador to Iraq, was appointed by President George W. Bush to the newly created position yesterday.
"It's going to be a tough job," said Mr Lee Hamilton, former vice chairman of the bipartisan commission that recommended creation of the job in response to the September 11th, 2001, attacks on New York and Washington.
"He's been a top diplomat. He's had some very difficult assignments and he'll need those diplomatic skills.
"But he's going to have to be very tough to take on struggles with the CIA, the DOD," he said. "The president is going to have to forcefully support the national intelligence director," added Mr Hamilton.
Former CIA director Mr Stansfield Turner, who served as US spymaster under former President Jimmy Carter, said it was not clear that Bush would back Mr Negroponte against Mr Rumsfeld given the Pentagon chief's long-standing influence over Mr Bush.
"We don't know whether he'll be that committed in this case. We certainly have to hope so, I don't believe it will work otherwise," Mr Turner told CNN.
Mr Rumsfeld's Pentagon controls 80 per cent of the intelligence budget and opposed the reform bill that created the new director's job.
The Pentagon has also begun to expand its intelligence operations into areas once dominated by the CIA.
But congressional officials believe Mr Bush signalled the required backing for Mr Negroponte yesterday by saying the nominee would lead a "unified" intelligence community, have broad budgetary powers and authority over intelligence collection and sharing.