A delegation of U.S. lawmakers led by Sens. John McCain (R-Ariz.) and Joe Lieberman (I-Conn.) arrived in Baghdad on Thursday to confer with U.S. and Iraqi officials.
McCain, a 2008 presidential hopeful, repeated his recent call to increase U.S. troop levels in Iraq. He told reporters the military should add 15,000 to 30,000 troops to its 140,000-member force, with a goal of stabilizing the country.
"The American people are disappointed and frustrated with the Iraq war, but they want us to succeed if there's any way to do that," McCain said, according to news agencies.
Explosions and gunfire erupted in the Iraqi capital throughout much of the day.
Authorities discovered the bodies of 45 men in Baghdad, all with gunshot wounds and some bearing signs of torture.
Gunmen allegedly attacked a vehicle convoy carrying Iraqi Vice President Adel Abdul Mehdi through western Baghdad. An ensuing 30-minute gun battle ended only after the intervention of U.S. and Iraqi forces, according to police. Government spokesman Ali Dabbagh downplayed the incident, telling reporters that the Shiite Muslim vice president was unharmed.
An Iraqi army convoy in western Baghdad was struck by a car bomb, which killed a soldier and a civilian bystander and injured seven. A roadside bomb targeting an Iraqi army patrol south of Baghdad killed one soldier.
A car bomb explosion near Hillah killed two civilians and injured six. An Iraqi demolitions expert died trying to defuse one of two car bombs discovered Thursday in Sadr City, the capital's mostly Shiite slum. A mortar round struck a house in Ur, a Shiite neighborhood of northern Baghdad, injuring six people.
Police in the shrine city of Najaf arrested six alleged insurgents said to be involved in a plot to harm senior Shiite clerics and damage religious sites.
Special correspondents in Baghdad and Hillah contributed to this report.