America's Democrats and Republicans are preparing for a bitter political battle as the US war commander in Iraq prepares to plead for more time to pacify the war-torn nation.
General David Petraeus will make a hotly anticipated appearance in Congress over the next two days, where he will face a hostile barrage from Democrats.
They'll be demanding to know if and when troops can come home from a four-year war that has killed more than 3,700 US soldiers, tens of thousands of Iraqis and cost half a trillion dollars.
The top US commander will argue that President George W Bush's contentious strategy announced in January of surging 28,500 extra troops into Iraq has slashed sectarian violence and should be extended.
"I expect him to say that. And I really respect him. And I think he's dead, flat wrong," Democratic Senator Joseph Biden, a contender in the 2008 White House race, told NBC television.
General Petraeus also was expected to accept gradual cuts in the 168,000-strong US garrison from early next year — although the reductions he has in mind are unlikely to satisfy anti-war Democrats.
"My sense is that we have achieved tactical momentum and wrested the initiative from our enemies in a number of areas of Iraq," General Petraeus wrote in a weekend letter to US forces, while expressing disappointment at the pace of political reconciliation in Baghdad.
Show resolve: Bush
Mr Bush has seized on a new video by elusive al-Qaeda mastermind Osama bin Laden to strengthen his case that the US must show resolve in Iraq, which he said was "a part of this war against extremists."
Monday is billed as the most high-profile appearance on Capitol Hill by a US commander since General William Westmoreland addressed both houses of Congress in 1967 on the state of the war in Vietnam — whose shadow looms large over today's debate on future strategy in Iraq.
Calls to stay the course in Iraq are "the same kind of thinking, actually, that got us mired in Vietnam," Democratic Senator John Kerry said on ABC television, calling the Iraq mission "disastrous."
But Iraqi government spokesman Ali al-Dabbagh, speaking in Baghdad, urged against a US withdrawal because the Iraqi government needs help to "prevent the return of the terrorists."
According to a Washington Post-ABC News poll, 60 percent of Americans do not believe that US forces are making significant progress towards restoring order in Iraq, while 58 percent believe the "surge" has made little difference.
Last week, a slew of US reports portrayed Iraq's government and security forces as dysfunctional, unwilling or unable to take on the sectarian militia threatening to tear the bloodstained country apart.
Republican White House runner John McCain said he was "guardedly optimistic" that if the surge continues, "you could see a messy but favourable outcome."
Warning of the regional consequences of failure in Iraq, Senator McCain said: "And I am convinced that it will be chaos, genocide, and we'll be back with greater sacrifice."
With the political heat rising ahead of national elections next year, there are reports of dissent even among top military commanders over the surge policy.
General Petraeus has clashed bitterly with his military superior Admiral William Fallon, who believes the tactic is using up valuable troops needed elsewhere across the Middle East, according to reports in the Washington Post.