Even before Gen. David Petraeus and Ambassador Ryan Crocker reach Capitol Hill to deliver their progress report on benchmarks in Iraq, U.S. politicians were using their appearance to stake ground in the ongoing debate over the U.S. military presence there.

Petraeus, the head of Multinational Forces in Iraq, and Crocker are spending two days testifying in front of four committees, starting with a joint House Armed Services/International Relations panel hearing at 12:30 p.m. EDT on Monday.

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Their testimony is a prelude to remarks by President Bush later in the week that are likely to indicate the administration's intention for the nearly 170,000 troops based in Iraq.

Democrats opposed to a strong, continued military presence have already labeled the report unreliable and suggested that Petraeus, the head of Multinational Forces in Iraq, either can't be objective or isn't informed enough to speak of Iraq's political will.

"You've got a ministry of the interior that has a police force that's corrupt and ineffective. There are some improvements in the army, that's true. But there has been no progress with respect to the Sunnis. Ethno-sectarian hatred is certainly as high, if not higher. The statistics are very questionable," Sen. Dianne Feinstein, D-Calif., told "FOX News Sunday."

"There was a big disconnect between the truth of the matter and the reality. I mean, the truth of the matter is that ... this administration's policy and the surge are a failure," said Sen. Joe Biden, chairman of the Senate Foreign Relations Committee and a 2008 presidential candidate.

Republicans under pressure to start surrendering their support for the war, have responded in varying degrees. But two strong supporters who spoke on Sunday said they will listen with open minds to the testimony, and aren't ready for any "political redeployment."

"I am guardedly optimistic that if we send the message that we are there to win and let this surge continue, then I think you could see a messy but favorable outcome," Sen. John McCain, R-Ariz., also a 2008 presidential candidate, told ABC's "This Week."

"One thing we've learned — you don't need a de-Baathification law to beat Al Qaeda. You don't need a local election law to diminish Al Qaeda," said Sen. Lindsey Graham, R-S.C., who appeared with Feinstein. "The one thing for sure ... I'm not looking for political redeployment."

According to officials familiar with the upcoming remarks, the two advisers will note that while national political progress in Iraq has been disappointing, security gains in local areas have shown promise.

Those officials told The Associated Press that Petraeus and Crocker will say the spring surge of 30,000 troops has done more to help Iraq get on its feet than any previous effort to quell the insurgency and restore stability. The officials rejected suggestions that Petraeus and Crocker would recommend anything more than a symbolic reduction in troop levels and then only in the spring when troop rotations are already expected.

The impending report is based on 18 benchmarks for progress, half political and half military. A July pre-report assessment said the Iraqis were making satisfactory progress on eight benchmarks while failing to achieve progress on another eight. Two had mixed results.

But the Government Accountability Office issued its own report last week that showed Iraq had achieved only three of the 18 benchmarks and had made some progress on four others. GAO's director told Congress on Friday that Iraq's prolonged political stalemate could undermine military gains achieved by the troop surge.

"There has clearly been a significant delay in the Iraqi government being able to meet its milestones, and that's the area of probably greatest disappointment is the lack of political progress," said GAO Comptroller-General David Walker.

Another report released last week by an independent commission led by retired Marines Gen. James Jones and former Washington, D.C. police chief Charles Ramsey presented an optimistic assessment of the ability of Iraqi security forces to stand up in order for the American troops to stand down, but stressed that tactical success will not be accomplished for several more years.

"We think that over the next year, year-and-a-half, they will be able to increasingly bring greater security internally against the terrorists," Jones told NBC's "Meet the Press." The general said that the army's evolution will come in two parts — first through beating back insurgents and terrorists and later by moving toward border security and defense of the nation.

The army shift from domestic enforcement to national security will occur when the police force, which is currently corrupted by sectarian factions, is able to take over internally, Jones said. But that won't be a likely scenario for another three to four years and will be largely dependent on the ability of Iraq's government to achieve "genuine national reconciliation."

"It's probably a three to four year project for them. ... It depends on what the external threats are," he said. "There's no magic formula here. It depends on the rate of progress, it depends on the international ability to convince Iran and Syria to help rather than hinder the recovery in Iraq, and that's not happening right now."

That kind of timeframe was not acceptable to Biden and others.

"We have been a crutch too long. So what we have to do now is to change that. And the way to change that is to start bringing our troops," said Sen. Ted Kennedy, D-Mass., who has been strongly against the Iraq war from the onset

Kennedy, appearing on CBS' "Face the Nation," called the current strategy a "cockamamie policy" and said U.S. soldiers are being "held hostage" to Iraq politicians.

Biden also rejected a recent letter from Petraeus to his troops in which he wrote: "My sense is that we have achieved tactical momentum and wrested the initiative from our enemies in a number of areas of Iraq. We are, in short, a long way from the goal line, but we do have the ball and we are driving down the field."

"I really respect him. And I think he's dead, flat wrong. The fact of the matter is that there is — that this idea of these security gains we've made have had no impact on the underlying sectarian dynamic. None. None whatsoever," said Biden, who was on "Meet the Press."

Biden and other Democratic lawmakers have suggested they want a firm date for departure.

"I believe in a start date and a target date by which to have troops withdrawn, all those but are necessary to protect civilians that remain there, and all but those needed to prevent Al Qaeda from gaining large swaths of territory," Biden said.

"The problem is, if you don't have a deadline and you don't require something of the Iraqis, they're simply going to use our presence as cover for their willingness to delay, which is what they have done month after month after month," said Sen. John Kerry, D-Mass.

But Gen. Brent Scowcroft, former national security adviser to President George H.W. Bush and a critic of the 2003 invasion, said any effort to pull troops out in the short term would leave the region in a "very vulnerable state."

"I think that Iraq is surrounded by strong neighbors for the region, all of whom have a vital interest in how Iraq turns out. If we were to walk away, I think we could very well have a region that looks like Iraq looks now, because of the conflicting interests of the parties in the region," Scowcroft said. "Any withdrawal should be consequent to the situation on the ground, not to a calendar."

"If the general tells me down the road we can withdraw troops because of military success, we should all celebrate it," Graham said of Petraeus. "But if politicians in Washington pick an arbitrary date, an arbitrary number to withdraw, it's not going to push Baghdad politicians. It's going to re-energize an enemy that's on the mat."

In the run-up to the report, several war opponents have sought to portray Petraeus as a Bush lackey who will say whatever the administration wants. Sens. Harry Reid and Dick Durbin, the No. 1 and 2 Democrats in the Senate, suggested last week that Petraeus is a liar.

"I first met General Petraeus when I went to Iraq. At that time he was training Iraqi troops, he told us at that time it was going great. They'd be able to take over the country themselves. That was three years ago," Reid said.

Liberal group MoveOn.org has also taken out a full-page ad in Monday's New York Times that accuses Petraeus of "cooking the books" on Iraq.

The White House called the ad "boorish" and childish." White House press secretary Tony Snow said Monday the ad is a pre-emptive attempt to smear the general before he has testified, and members of Congress "ought to be out condemning it."

For the most part, both Democratic and Republican senators rejected the characterizations.

"I don't buy into that. He's an honorable guy," Biden said. "He's stating the parts he believes is true."

"Just makes me sad. Makes me very sad. A person who has dedicated his life to the service of his country, he was wounded in three wars, he's one of the finest examples of military service. ... He served his country with honor and distinction, and if we have to sink to that level to besmirch the reputation of a very fine and wonderful American, then I lament the level of dialogue," McCain said.

"General Petraeus is greatly respected. ... and there's no question that he is a fine and brilliant general," Feinstein said. "But I don't think he's an independent evaluator."FOX News' Major Garrett, John Brandt and Sharon Kehnemui Liss and the Associated Press contributed to this report .