The governor of the Baghdad (search) region, known for cooperating closely with American troops, was assassinated along with six bodyguards as he drove to work Tuesday in yet another bloody day of insurgent attacks that exposed grave security flaws in Iraq with elections less than a month away.

Other assaults Tuesday killed five American troops as well as eight Iraqi commandos and two civilians, bringing the death toll in the last three days to more than 70. Despite the violence, which U.S. troops and Iraqi security forces have been helpless to prevent, American and Iraqi leaders insist the Jan. 30 vote would go forward.

White House spokesman Scott McClellan (search) acknowledged security "challenges" in Iraq but said the election timetable would not be changed.

"For much of the country, the situation is secure enough to move forward on holding elections," McClellan said. "There are a few areas that we're continuing to work to improve the security situation, so those areas will be able to have as full a participation as possible in elections."

While it's true that many areas of Iraq are calm, there are vast regions, including the capital, that are extremely dangerous. In places like Fallujah (search), which was bombed to ruins in a U.S.-led campaign in November, and the northern city of Mosul, there has been little headway in preparing for the vote.

The attacks have prompted Sunni Arab clerics to call for a boycott, and Iraq's largest Sunni political party announced it was pulling out of the race because of poor security.

The country's Shiites, many of whom are in the government, want to take power but they also want the Sunnis to participate in the vote. A low turnout because of the fear of violence or a Sunni boycott could undermine the legitimacy of the country's first free elections since the overthrow of the monarchy in 1958.

McClellan confirmed that President Bush spoke with interim Prime Minister Ayad Allawi on Monday, but said they did not discuss postponing the vote. They focused on "some of the ongoing challenges as Iraq moves forward toward a free, democratic and peaceful future," he said.

Several Iraqi leaders, including the defense minister and the ambassador to the United Nations, have suggested a delay as a way to get Sunnis to take part, but other officials support Allawi and want the vote to be held on time.

"So far, there is no postponement ... of the elections, and they will be held on Jan. 30," Foreign Minister Hoshyar Zebari told reporters. He acknowledged the vote will "take place under very difficult circumstances, which will be a big challenge for all Iraqis and their government."

Those challenges were made clear yet again Tuesday.

The militant group of Jordanian terrorist Abu Musab al-Zarqawi, Al Qaeda in Iraq, claimed responsibility for killing Gov. Ali al-Haidari and his bodyguards, according to a statement posted on a Web site known for carrying such claims.

"We tell every traitor and supporter of the Jews and Christians that this is your fate," the statement said. Its authenticity could not immediately be verified.

Al-Haidari's three-vehicle convoy was passing through Baghdad's northern neighborhood of Hurriyah when gunmen opened fire, said the chief of his security detail, who asked to be identified only as Maj. Mazen.

"They came from different directions and opened fire at us," Mazen said, reached on al-Haidari's cell phone.

Al-Haidari was the target of an assassination attempt last year that killed two of his bodyguards. He is the highest-ranking Iraqi official killed since the former president of the now defunct Governing Council — Abdel-Zahraa Othman, better known as Izzadine Saleem — was assassinated in May.

Al-Haidari worked closely with the U.S.-led multinational forces on rebuilding the capital. In an interview published Tuesday in al-Mutamar newspaper, he said infrastructure in Baghdad was improving because of cooperation between his office and the troops.

In Thailand, Secretary of State Colin Powell said he was saddened by al-Haidari's death.

"It once again shows that there are these murderers and terrorists, former regime elements in Iraq, who don't want to see elections," Powell said. "They want to go back to the tyranny of Saddam Hussein's regime, and that's not going to happen."

In the American deaths, a roadside bomb killed three U.S. soldiers in Baghdad, and a soldier and a Marine were killed in other attacks outside the capital, the U.S. military said.

The three soldiers killed in the capital were with Task Force Baghdad, and two soldiers were wounded in the attack, the military said.

Elsewhere, a roadside bomb attack killed one 1st Infantry Division soldier and wounded another near Balad, 50 miles north of Baghdad.

A U.S. Marine assigned to the 1st Marine Expeditionary Force was killed in action in restive Anbar province, which includes Fallujah.

The attacks made it the deadliest day for the U.S. military in Iraq since a bombing at a mess tent in Mosul on Dec. 21 killed 22 people, including 14 U.S. soldiers and three American contractors.

Also Tuesday, a tanker truck packed with explosives blew up near an Interior Ministry commando headquarters in western Baghdad, killing 10 people and wounding about 60, the ministry said. Zarqawi's Al Qaeda in Iraq claimed responsibility for that attack as well.

A suicide driver rammed the truck at a police checkpoint near the headquarters, which is also near an entrance of the Green Zone, the fortified home of the U.S. Embassy and the interim government. Eight Iraqi commandos and two civilians were killed, the Interior Ministry said.

Later, a roadside bomb killed three Iraqi National Guardsmen and wounded two near Baqouba, 35 miles northeast of Baghdad, U.S. military spokesman Neal E. O'Brien said.

Such suicide car bombs have become tragically routine in Baghdad, the blasts echoing across the city almost every morning along with the sound of small-arms fire and mortar and rocket attacks.

Tuesday's attacks came a day after violence that saw a roadside attack and three car bombs, one near the prime minister's party headquarters in Baghdad and others targeting Iraqi troops and a U.S. security company convoy. At least 16 people were killed Monday.

A car bomb near the Green Zone killed three Britons and an American working for U.S. security firms, their employers and Britain's Foreign Office said Tuesday.

The blast killed two British employees of U.S. security firm Kroll Inc., said Andrew Marshall, a London-based spokesman for the firm. A third Briton and an American employed by another U.S. firm, BearingPoint, also were killed, that company said.

The American was identified as Tracy Hushin, 34, who was working under contract for the United States Agency for International Development.