General George Casey said on Thursday that the war-torn country was in a period of heightened uncertainty that made it "too soon to tell" if troops can be brought home.
In March and again in July, the man who commands the 147,000 US troops in Iraq has predicted a "fairly substantial" reduction in American forces in early 2006 if Iraq's political process goes positively and progress is made in developing Iraqi security forces.
Pentagon officials said that meant a reduction of perhaps 20,000 to 30,000 troops.
But after briefing US lawmakers behind closed doors on Capitol Hill, Casey was more cautious when asked whether the troop reduction was still possible.
"I think right now we're in a period of a little greater uncertainty than when I was asked that question back in July and March," Casey told reporters.
Wait and see
Noting that Iraqis vote on a draft constitution in a 15 October referendum and, if they endorse it, then elect a new government on 15 December, the general added: "This constitutional referendum and whether it is supported by the Sunnis to a large degree, I think, is something that we just have to watch to see how that comes out."
"So until we're done with this political process here, with the referendum and the elections in December, I think it's too soon to tell."
The draft constitution largely reflects the views of the Shia Muslim community and the Kurds leading the US-backed Iraqi government rather than the views of Sunni Arabs who controlled Iraq under deposed President Saddam Hussein.
Iraq's insurgency draws the bulk of its support from the Sunni Arab community.
"There was nothing that we heard today to suggest that we are coming out of Iraq soon," Illinois Democratic Senator Richard Durbin told reporters. "There is no indication from the president or the leadership that they have a plan that will
bring our troops home soon."
"And in terms of the capability of the Iraqis to fend for themselves, defend their country, there's been no clear indication from this administration that they have the stand-up capability to do that. And until that happens, there is no end in sight," Durbin added.
Violence in Iraq continued unabated. There have been 1922 US military deaths in the two and a half years since US-led forces invaded Iraq in March 2003 in a war whose primary justification offered by Bush was ridding Iraq of weapons of mass destruction. No such weapons were found.