At least 112 people were killed nationwide, following a week that had already seen hundreds of deaths.
Walid Moallem, the highest level Syrian official to visit since the 2003 ouster of Saddam Hussein, on Sunday denounced terrorism in Iraq even as Washington mulled its own overture to Damascus for help in ending Iraq's violence.
Syria and Iraq share a long and porous desert border and both Baghdad and Washington have accused Damascus of not doing enough to stop the flow of foreign Arab fighters.
Moallem spoke at the end of a day that saw suspected Sunni Muslim bombers kill at least 33 Shiites and the kidnapping of a deputy health minister — believed the senior-most government official abducted in Iraq. Many Sunni attackers are believed to have infiltrated from Syria.
In Washington, Sen. John McCain said that without additional troops to ensure victory in Iraq, the United States could find itself more vulnerable to terrorist attacks at home.
McCain, a front-running Republican hopeful for the 2008 presidential elections, said the United States must send an overwhelming number of troops to stabilize Iraq or face more attacks — in the region and possibly on American soil.
"I believe the consequences of failure are catastrophic," said McCain. "It will spread to the region. You will see Iran more emboldened. Eventually, you could see Iran pose a greater threat to the state of Israel."
McCain said he based his judgment partly on the writings of Abu Musab al-Zarqawi, the al Qaeda leader in Iraq who was killed in a U.S. air raid, and of Osama bin Laden.
"The consequences of failure are so severe that I will exhaust every possibility to try to fix this situation. Because it's not the end when American troops leave. The battleground shifts, and we'll be fighting them again," McCain said. "You read Zarqawi, and you read bin Laden... It's not just Iraq that they're interested in. It's the region, and then us."
A suicide bomber in the predominantly Shiite city of Hillah south of Baghdad lured men to his KIA minivan with promises of a day's work as laborers, then blew it up, killing at least 22 and wounding 44, police said.
Babil province police Capt. Muthana Khalid said three suspected terrorists, two Egyptians and an Iraqi, were arrested on suspicion of planning the suicide attack with the bomber, a Syrian.
Within hours, a roadside bomb and two car bombs exploded one after another near a bus station in Mashtal, a mostly Shiite area of southeastern Baghdad, killing 11 and wounding 51, police said.
Besides the victims of the bombings in Hillah and Baghdad, at least 23 other people were killed nationwide. In addition, the bodies of 56 murder victims, many of them tortured, were dumped in three Iraqi cities, 45 of them in Baghdad alone.
Also Sunday, gunmen kidnapped Iraq's deputy health minister from his home in northern Baghdad, the Iraqi army and police reported. They said the gunmen wore police uniforms and arrived in seven vehicles to abduct Ammar al-Saffar, a Shiite.
Al-Saffar was snatched nearly a week after dozens of suspected Shiite militia gunmen in police uniforms kidnapped scores of people from a Ministry of Higher Education office in Baghdad. That ministry is predominantly Sunni.