An Iraqi military spokesman said, meanwhile, that militants fleeing the crackdown have made areas outside the capital "breeding grounds for violence," spreading deadly bombings and sectarian attacks to areas once relatively untouched.
McCain, who is seeking the Republican presidential nomination, was combative during a press conference in the military's media center in the heavily guarded Green Zone, and responded testily to a question about remarks he had made in the United States last week that it was safe to walk some Baghdad streets.
"The American people are not getting the full picture of what's happening here. They're not getting the full picture of the drop in murders, the establishment of security outposts throughout the city, the situation in Anbar province, the deployment of additional Iraqi brigades which are performing well, and other signs of progress having been made," said McCain, of Arizona.
In the latest violence, a bomb struck a popular market in Tuz Khormato, 130 miles north of Baghdad, killing three people and wounding four. It was the second attack in the city in as many days after two Iraqis seeking work were killed in a car bombing on Saturday.
Brig. Gen. Qassim al-Moussawi promised the recent attacks would not derail the neighborhood-to-neighborhood sweep that began in Baghdad on Feb. 14.
He acknowledged an increase in violence outside Baghdad even as the death toll is down in the capital but said the security crackdown was providing an example of how to fight it.
"The fact that the violence decreased in Baghdad, the terrorists went to the surrounding areas and these areas are breeding grounds for violence," he said. "The terrorist elements are backed into a corner and we are going to continue to carry out these operations."
McCain said the Republican congressional delegation he led to Iraq drove from Baghdad's airport to the center of the city, citing that as proof that security was improving in the capital. Prominent visitors normally make the trip by helicopter.
The delegation was accompanied by heavily armed U.S. troops when they were not in the Green Zone, site of the U.S. Embassy and Iraqi government. They traveled in armored military vehicles under heavy guard.
Sen. Lindsey Graham, a South Carolina Republican, criticized congressional Democrats who passed spending legislation that would set deadlines for pulling U.S. forces out of Iraq. He said President Bush would veto the measures and should.
"It will be a huge mistake to set a deadline. It (the U.S. troop surge) is working. We are doing now what we should have done three years ago. ... The Iraqi people want their own destiny but they don't have the capabilities yet," he said.
Delegation members, who included Rep. Mike Pence, a Republican from Indiana, and Rep. Rick Renzi, an Arizona Republican, spoke glowingly of an hour they spent in the Bab al-Sharqi market, which was hit by a suicide bomber on Jan. 22. At least 88 people died in the attack.
The congressmen said they were impressed with the resilience and warmth of the Iraqi people, some of whom they said would not take their money for souvenirs the delegation bought.
Speaking at a joint news conference with al-Moussawi, U.S. military spokesman Rear Adm. Mark Fox also expressed confidence in the security sweep, saying half of the U.S. troop reinforcements are in place, but he warned it would not be easy to pacify the capital and asked for patience.
"The effort to exert security in Iraq will take time," Fox said. "Our job will not be accomplished within days or weeks."
"We are going to see more violence in the coming weeks and months," he added.
More than 600 Iraqis have been killed in sectarian violence since March 25, most in a series of high-profile suicide bombings. Among them were at least 152 people killed in a suicide truck bombing in Tal Afar — the deadliest single strike since the war started four years ago. That bombing was followed by a shooting rampage against Sunnis that left at least 45 people dead.
Vice president Tariq al-Hashimi called on Sunnis and Shiites to abandon acts of revenge and live together in peace.
In a televised speech marking the Prophet Muhammad's birthday, al-Hashimi, a Sunni Muslim, called for reviewing the status of detainees "so that those who are innocent be released."
Thousands of suspected insurgents and militia members are being held in detention centers run by Iraqi and foreign forces.
Underscoring security concerns, Fox said two suicide vests were found unexploded Saturday in the Green Zone, less than a week after a rocket attack killed two Americans in the vast central area. Fox said the matter was under investigation, and al-Moussawi declined to comment on where the vests were found.
In other violence Sunday, two top Sunni officials escaped an assassination attempt in one Baghdad's most restive neighborhoods.
Omar Abdul-Sattar of the National Accordance Front, the biggest Sunni parliamentary block with 44 seats, and Omar al-Jubouri, an aide to Sunni Vice President Tariq al-Hashemi, were targeted by a roadside bomb when their convoy was passing through Yarmouk in western Baghdad, police said. Nobody was killed in the attack, but it came amid a recent rise in violence by suspected Sunni insurgents against members of their minority Islamic sect who are affiliated with the political process.
Separately, Kurdish lawmakers struck back against criticism over the Iraqi government's decision to endorse plans to relocate thousands of Arabs who were moved to the northern city of Kirkuk as part of Saddam Hussein's campaign to force ethnic Kurds out of the oil-rich city, in an effort to undo one of the former dictator's most enduring and hated policies.
Almost immediately, opposition politicians said they feared the plans would harden the violent divisions among Iraq's fractious ethnic and religious groups and possibly lead to an Iraq divided among Kurds, Sunni Arabs and Shiites.
The plan was virtually certain to anger neighboring Turkey, which fears a northward migration of Iraqi Kurds — and an exodus of Sunni Arabs — will inflame its own restive Kurdish minority.
The Kurds warned that derailing the decision, which could pave the way for a referendum on the city's fate as required by the constitution, "will put Iraq's unity at risk."
"Those who are putting sticks in the wheel of the political process are those who are calling for derailing this article," Saad al-Barzanchi, a Kudish lawmaker with the Kurdish parliamentary bloc that holds 53 seats. "This is not a negotiable matter. To those who want to derail it ... we say: This is an alarm bell and threatens Iraq's unity."