McCain made his remarks in Baghdad, where he and five other U.S. Congress members are meeting with U.S. and Iraqi officials.
McCain said he agrees with a recent U.S. Iraq Study Group report that describes the situation in Iraq as "grave and serious."
"I'd like to say that I believe conditions have improved," he said, but "certainly, in Baghdad, they have not. I believe that there is still a compelling reason to have an increase in troops here in Baghdad and in [Al-]Anbar Province."
In other news, gunmen wearing police uniforms kidnapped several dozen traders from a commercial area of the Iraqi capital, Baghdad, but later in the day released at least 25 of the hostages. The gang had attacked a busy shopping district, stealing cash from shops and seizing hostages, apparently all Shi'ites. It is unclear how many people are still held captive.
Also today, the Iraqi authorities reported that two police officers were killed and four civilians were wounded on December 12, when police unsuccessfully tried to defuse explosives planted in a car in eastern Baghdad.