Sunday's deadly missile hit on a US military helicopter increases the urgency of capturing or killing Saddam Hussein, say the Bush hawks.
Paul Bremer and Donald Rumsfeld both hinted the former dictator could be providing inspiration for, or even have had a direct hand in the attacks.
Officials, including Rumsfeld, are investigating what role Saddam Hussein might be playing in the surge of violence in Iraq.
That speculation heightened following the deaths of 15 soldiers whose Chinook helicopter was shot down and in the wake of the bloodiest week of the six month-long coalition occupation.
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Senator Pat Roberts, chairman of the powerful Senate Intelligence Committee, told CNN television: "I think Saddam Hussein is playing a role - if nothing else (in terms of) the palpable fear on the part of the Iraqis of Saddam Hussein and the fear that he might come back."
That view was echoed by US Secretary of Defence Donald Rumsfeld.
"We do not have hard evidence that he is coordinating this," he told US television.
But he quickly added: "The fact that he's not been captured or killed is important ... He's not coming back, but until he's dead or captured, there is that concern," Rumsfeld said.
Paul Bremer the US adminstrator for Iraq said that US investigators are looking for signs of Saddam's direct involvement.
"In our examination of intelligence, we look for that," he said, but so far, "we do not see evidence of that yet.
"At this point, have no evidence that Saddam himself is behind this. It can't be excluded," he said.
The top Democrat on the Senate Intelligence Committee, meanwhile, agreed that capturing Saddam Hussein ought to be a top priority for US forces in Iraq, in light of recent attacks.
"We ought to bring him down," Senator John Rockefeller told CNN. "I think now that's becoming an enormously important question in Iraq.
"Whether he's in charge of command and control ... he may or may not be," the West Virginia Democrat said. "I have to lean on the more gloomy, side and that is that he does have something to do with that," Rockefeller said.