WASHINGTON – General David Petraeus went before Congress today to deliver his long-awaited assessment of Iraq, greeted by Democrats who praised him while sharply criticizing the war he commands.

The four-star general sat a few feet away as Rep. Ike Skelton, Democrat of Missouri, described him as “almost certainly the right man for the job in Iraq.” But, he added, “he’s the right person three years too late and 250,000 troops short.”

Rep. Tom Lantos, Democrat of California, hailed General Petraeus and a second witness, Ambassador Ryan Crocker, as “two of our nation’s most capable public servants.”

And yet, he quickly said, “military progress without political progress is meaningless….We need to get out of Iraq, for that country’s sake and for our own.”

Mr. Skelton is chairman of the House Armed Services Committee, while Mr. Lantos chairs the House Foreign Affairs Committee.

Rep. Duncan Hunter of California was the first Republican to speak, and he criticized unnamed Democrats for having criticized General Petraeus in advance of the nationally televised hearing.

He said the military gains in recent months had produced gains by Iraqis, including an army that is “beginning to emerge as a professional force.”

The introductory remarks by the lawmakers reflected the deep divisions in Congress over a war that has claimed the lives of more than 3,700 American troops.

General Petraeus patiently listened to the politicians for a time before he could speak, the commander of 165,000 troops also heckled and criticized by anti-war critics.

“Tell the truth, general,” shouted protesters as the four-star general made his way into the crowded hearing room.

General Petraeus did not respond, either to them or to the sole heckler who interrupted the session in its opening seconds.

Mr. Skelton ordered the room be cleared of protestors. “Out they go,” he said.

A moderate midwesterner, Mr. Skelton blended his praise for the general with sharp questions about the military mission he leads.

“Tell us why we should continue sending our young men and women to fight and die if the Iraqis won’t make the tough sacrifices leading to reconciliation.”

“… Are we merely beating a dead horse?” the congressman asked.

General Petraeus’ greeting elsewhere wasn’t nearly as warm as Mr. Skelton’s praise.

“Cooking the books for the White House,” charged the newspaper advertisement by MoveOn.Org — an allegation that Republicans swiftly challenged Democrats to disavow.

“These childish tactics are an insult to everyone fighting for our freedom in Iraq, and they should be condemned,” Senator McConnell of Kentucky said.

The ad and ensuing political scuffling served as a backdrop for General Petraeus’s long-awaited assessment of troop buildup that President Bush ordered last January.

“It has not worked out as we had hoped,” the four-star general wrote the men and women under his command late last week. He said that the pace of political reform among Iraqi politicians has been disappointing.

Among the major unanswered questions as General Petraeus settled into the witness chair was how many American troops could begin to withdraw, and how quickly.

Democrats generally favor more, and faster. So far, Republicans have been generally willing to stick with Mr. Bush, who has argued insistently against a withdrawal deadline.

The appearance of General Petraeus, more than Mr. Crocker, took on outsized importance. As both the architect and the commander of last winter’s shift in strategy, he has won praise from lawmakers in both parties, and opinion polls show he has more credibility with the public on the war than Mr. Bush.

Democrats have been critical of General Petraeus, but not nearly as scathing — or as personal — as the MoveOn advertisement.

“General Petraeus or General Betray Us?” it asked, a wordplay on his name.

Yesterday, Democrats sharply questioned Bush administration assertions that seven months of troop increases might be working, citing continuing violence and Prime Minister al-Maliki’s political woes. They said they would not back off efforts to set target dates for bringing troops home.

“The reality is that, although there has been some mild progress on the security front, there is, in fact, no real security in Baghdad or Anbar province,” Senator Biden, Democrat of Delaware, a 2008 presidential candidate who chairs the Senate Foreign Relations Committee, said.

Senator Arlen Specter, Republican of Pennsylvania, said he respected General Petraeus’s judgment but would not blindly follow it.

“We’re going to look behind the generalizations that General Petraeus or anybody gives us and probe the very hard facts to see exactly what the situation is,” Mr. Specter said. “As I’ve said in the past, unless we see some light at the end of the tunnel here, very closely examining what General Petraeus and others have to say, I think there’s a general sense that there needs to be a new policy.”

In their long-awaited report to Congress, General Petraeus and Mr. Crocker will say the buildup of 30,000 troops, which brings the American total to nearly 170,000, is working better than any previous effort to quell the insurgency and restore stability, according to the officials who spoke on condition of anonymity because they were discussing internal deliberations.

The officials also disputed suggestions that General Petraeus and Mr. Crocker would recommend anything more than a symbolic reduction in troop levels and then only in the spring.

The testimony sets the stage for an announcement by Mr. Bush later in the week about how he will proceed in the face of growing congressional discomfort with the war.

The hearing happened as a poll released today showed that an overwhelming numbers of Iraqis say the American troop buildup has worsened security and the prospects for economic and political progress in their country.

Of those surveyed in a poll conducted by ABC News, Britain’s BBC, and Japan’s public broadcaster NHK, 47% said they want American forces and their coalition allies to leave the country immediately. This was 12% more people than harbored those views in a March poll, just as the troop increase was beginning. And 57% — including nearly all Sunnis and half of Shiites — said they consider attacks on coalition forces acceptable, a slight increase over the past half year.