Antiwar lawmakers were not swayed by Gen. David Petraeus' announcement that he's planning on ordering home one Marine unit from Iraq at month's end and another Army brigade in mid-December.

Petraeus, the head of Multinational Forces in Iraq, and U.S. Ambassador to Iraq Ryan Crocker testified to a joint hearing of Congress Monday. Petraeus predicted a drawdown of U.S. troops in Iraq by next summer to pre-surge levels, but he would not offer numbers beyond July.

Watch FOX News at 9 p.m. ET for an exclusive one-hour interview by Brit Hume with Gen. Petraeus and Amb. Crocker.

"I believe that we will be able to reduce our force to the pre-surge level of brigade combat teams by next summer without jeopardizing the security gains that we've fought so hard to achieve," Petraeus told a joint hearing of Congress

"Our experience in Iraq has repeatedly shown that projecting too far into the future is not just difficult, it can be misleading and even hazardous," Petraeus added.

Petraeus said the total number of troops to be withdrawn by next summer — one Marine expeditionary unit, two Marine battalions and five Army brigades in all — is a "substantial" withdrawal that would allow the remaining forces to continue operational and strategic considerations, including fighting off Al Qaeda in Iraq and Iranian "militia extremists."

The numbers didn't satisfy many Democratic lawmakers, several of whom called called Petraeus' testimony to Congress the wicked work of the White House.

"General Petraeus has been tasked with stalling Congress to keep the troops in the middle of a civil war. General Petraeus has failed to give Congress an independent assessment of the Iraq war. His statement sounds like the president's talking points," said Rep. Dennis Kucinich, D-Ohio, a 2008 presidential candidate..

"Our brave American service men and women are sacrificing daily for a policy that has no end in sight. A policy of more of the same is no strategic vision, strains our military to the breaking point, and enables Iraqi leaders to dither endlessly instead of reaching a political consensus over the future of their country," said Rep. Chris Van Hollen, D-Md.

"No amount of sugar coating and spin can change one simply fact -- four years after the president’s invasion of Iraq our troops are caught in the midst of a civil war with no end in sight, and it’s up to the US Congress to use the power of the purse to force the President to bring them home," said Rep. Lynn Woolsey, D-Calif., a longtime opponent of the war.

But Petraeus said a quick departure from Iraq would allow Al Qaeda in Iraq to regain its faltering foothold, and a premature withdrawal would leave instability in many areas that are now achieving sustainable security.

The general said the number of "security incidents" and civilian deaths in Iraq is on the decline and the number of Iraqi forces standing up to fight has increased in the last 12 weeks. He said the overall number of security incidents in the last two weeks was at the lowest levels since June 2006.

"As a bottom line up front, the military objectives of the surge are in large measure being met," Petraeus said, adding that "Iraqi elements have been standing and fighting and sustaining tough losses, and they have been taking the lead in operations in many areas."

Petraeus told a packed committee room that the tribal rejection of Al Qaeda in Anbar province has spread to other areas of the country, and while competition among ethnic and sectarian communities for power and resources continues, the issue is whether "competition takes place more or less violently" in the coming months.

Petraeus warned, however, that Iran is trying to use its Iranian Revolutionary Guard into a "Hezbollah-like" militia in Iraq.

"It is increasingly apparent to both coalition and Iraqi leaders, that Iran, through the use of the Quds force, seeks to turn the Iraqi special groups into a Hezbollah-like force to serve its interests and fight a proxy war against the Iraqi state and coalition forces in Iraq," Petraeus said, adding that the Quds force has been connected to kidnappings of Iraqi officials, U.S. troop deaths — using Iranian-provided explosives — and civilian rocket attacks in Baghdad's Green Zone.

Petraeus was testifying with Crocker at a joint hearing of the House Armed Services and Foreign Affairs committees. The progress report on benchmarks in Iraq was required in legislation enacted after President Bush announced a troop surge in January. Bush is expected to follow their two days of testimony with an announcement indicating his plans for the nearly 170,000 troops based in Iraq. Bush remained mostly out of sight ahead of the testimony but called Prime Minister Nouri al-Maliki ahead of the hearing.

Crocker, whose report to Congress on political benchmarks is considerably harder to deliver, was not as upbeat as Petraeus, saying Iraq "is and will remain for a long time to come a traumatized society."

He said the country's pressing problems "will take longer than we originally anticipated because of the environment and the gravity of the issues before them. Prime Minister Maliki and other Iraqi leaders face enormous obstacles in their efforts to govern effectively. I believe they approach the task with a deep sense of commitment and patriotism."

Crocker said debate continues in Iraq over whether a strong central authority or provincial rule is the best solution for a highly factionalized nation. He suggested that "provisional immunity" is helping deBaathification, and the "seeds of reconciliation are being planted." In all his discussions with disparate leaders, however, they have agreed that they need Multinational Forces to remain while they sort out their disputes, he said.

The ambassador couched his testimony by saying any evaluation can only be made in the context of Iraq's recent history.

"Any Iraqi under 40 years of age — and that is the overwhelming majority of the population — would have known nothing but the rule of the Baath party before liberation four and half years years ago," Crocker said, adding that support for local empowerment is a nascent concept that is growing in varying communities.

"We've come to associate progress on national reconciliation as meaning the passage of key legislation. There is logic to this," Crocker said, adding that oil revenue-sharing laws "deal with deeper issues than whether Iraqis in oil producing areas are willing to share their wealth with other Iraqis."

Crocker warned that leaving Iraq will guarantee failure because Iran will step in to fill the vacuum.

"Iran plays a harmful role in Iraq," he said. "Our current course is hard. The alternatives are far worse."

At the start of Monday's hearing, the head of the House Armed Services Committee, Rep. Ike Skelton, praised Petraeus as the right man for the job of cleaning up Iraq, but said his call to service might have come too late in the war to be helpful.

"He's almost certainly the right man for the job in Iraq, but he's the right person three years too late and 250,000 troops short," said Skelton, D-Mo. "If we had your vision and approach, General, early on, we might not have gotten to the point where our troops are caught in the midst of brutal sectarian fighting without the Iraqi government bridging the political divides that drive the violence.

"The surge was intended to provide breathing space ... while our troops are holding back the opposing team to let them make a touchdown, the Iraqis haven't even picked up the ball," Skelton continued.

Democrats opposed to an ongoing military surge have already labeled the report unreliable and suggested that Petraeus and Crocker were sent to convince Congress that victory is at hand when it is not.

"With all due respect to you, I must say, I don't buy it," said Rep. Tom Lantos, D-Calif.

Democratic presidential candidate Sen. Chris Dodd, who was not present at the hearing, issued a statement saying that "the fact that there are questions about General Petraeus' report is not surprising given that it was brought to you by this White House. In contrast, independent report after report indicates that the whack-a-mole strategy has made this the bloodiest summer of the war."

Lantos, chairman of the House Foreign Affairs Committee, said that everyone wants Petraeus to succeed, but he is working against not only insurgents in Iraq but public opinion at home.

"Every single one of us wants you to succeed in your efforts to the maximum possible extent," he said. "Our witnesses have been sent here this morning to restore credibility to a discredited policy. We, the American people, already know that the situation in Iraq is grim, and the growing majority of this Congress and the American people want our troops out."

Republican lawmakers began the hearing by excoriating liberal interest group MoveOn.org for running a full-page ad in The New York Times Monday calling the general "General Betray Us" and suggesting Petraeus was "cooking the books" to make the situation in Iraq to sound better than it is.

"I am distressed by the accusations leveled by some in the media and by some members of Congress during hearings like these calling into question the integrity of our military, accusing the military of cherry-picking positive numbers to reflect a dramatic decline in sectarian violence," said Rep. Ileana Ros-Lehtinen.

"Some in Congress accuse you, General Petraeus, of presenting a report that is simply White House propaganda. I have more respect for the military and for the military leaders' regard for the men and women whom they lead to believe that you would misrepresent the facts and alter conclusions to serve partisan purposes," she said.

In response to accusations that his testimony was crafted by the White House, Petraeus said no one had seen his statement to Congress until the moment he began speaking.

"This is my testimony, although I have briefed my assessment and recommendations to my chain of command, I wrote this testimony myself. It has not been cleared by nor shared with anyone in the Pentagon, the White House or the Congress until it was just handed out," he said.

Just as the hearing started, protesters, including antiwar poster child Cindy Sheehan and her sister Dee Dee Miller, were arrested outside the hearing room. Rev. Lennox Yearwood, founder of The Hip Hop Caucus, was also arrested and injured during an encounter with police.

Yearwood contends that it was his turn to enter the hearing room but police refused him entry. Witnesses on the scene said at least five officers "football tackled" him, prompting an ankle injury that warranted a response from D.C. Fire and Emergency.

Another protester arrested for disrupting the hearing was CodePink member Desiree Fairooz. She and another protester were kicked out of the room by Chairman Skelton for shouting in the opening seconds of the hearing.

The hearing was also interrupted when Petraeus was about to speak but his microphone wasn't working. During the lull as committee staff tried to sort out the technical malfunction, Skelton and Indiana Republican Rep. Dan Burton got into a tiff over allowing potential protesters to remain.

"I see a number of people in the audience that I anticipate will be making a disturbance, and if this occurs during the testimony by our honored guest, I hope you will be very firm and get them out of here," Burton said.

"You don't have to lecture me on it. They'll be gone," Skelton responded.

"Well, I still see them out there," Burton said.

"Don't worry about them. We've done this before. They'll display a sign, out they go," Skelton said, growing ever angrier at the technical delay in testimony. "We mean business, this is a very important hearing we're not about to have this nonsense go on, now or later."

Moments later, Skelton tossed out another shouting protester. The committee then recessed briefly to fix the audio problems.

When the hearing resumed and Petraeus finished his testimony, more CodePink protesters began shouting and were removed from the room.

"You are and you will throughout the remaining of this hearing be prosecuted" under D.C. law, Skelton said. "This is untolerable. We will not allow it."

FOX News' Chad Pergram and Sharon Kehnemui Liss contributed to this report.