Former US Secretary of State Colin Powell has said overstretched US troops are losing the conflict in Iraq.
Powell said the military was too overstretched to send extra troops
Mr Powell told CBS News that bolstering troop numbers would be unlikely to reverse the "grave and deteriorating situation" in the country.
President Bush is trying to shape a new strategy for Iraq, with officials suggesting more soldiers may be sent.
The recent Iraq Study Group review said the US strategy of "staying the course" was no longer viable.
It suggested combat troops could be withdrawn by early 2008.
But on Friday, an administration official said up to 25,000 more troops could be deployed in the country to try to help end the violence and make cities like Baghdad more secure.
There are currently 140,000 US troops in Iraq.
The leader of the Democrats in the US Senate has backed the reported plan to boost troop levels, but only if it is part of a longer-term strategy.
"If it is for a surge, that is, for two or three months, and if it is part of a programme to get us out of there as indicated by this time next year, then, sure, I'll go along with it," Harry Reid said.
However, Mr Powell told CBS he was not convinced more soldiers on the ground would quell the violence.
"I am not persuaded that another surge of troops into Baghdad for the purposes of suppressing this communitarian violence, this civil war, will work," he said.
He added that such was the overstretch of the US military, there were no additional troops that could be sent.
"We are losing - we haven't lost - and this is the time, now to start to put in place the kinds of strategies that will turn this situation around," he said.