Subhi Hassan, who handles political relations for the Patriotic Union of Kurdistan, and a bodyguard were killed Monday after unidentified gunmen chased down their car after it passed through a checkpoint, said Police Brigadier Ahmed Hawandi.
A third person in the car was wounded, Hawandi said, adding Iraqi police were investigating the shooting.
The shooting is the latest in a spate of killings that appear to be politically motivated and come in advance of the Jan. 31 Iraq-wide provincial elections.
Although violence is down 80 percent nationwide since early this year, U.S. officials say the security situation remains tenuous, and some areas of the country are still dangerous.
U.S. and Iraqi officials hope the elections will redress problems created by the last regional balloting in January 2005, when Sunnis largely stayed away from the polls.
As a result, Kurds and Shiites won a disproportionate share of the power, and Iraqi and U.S. military officials have expressed concern of a possible increase in violence prior to the election and after the balloting.
Last month, two political candidates in southern Basra were killed by unidentified gunmen and another was wounded in separate incidents. Earlier in December, Iraqi police said attackers stormed a home in Kirkuk and decapitated the leader of the women's league of the Kurdish Communist Party after breaking into her home.
The city of Kirkuk lies 180 miles north of Baghdad.
Also Tuesday, the U.S. military said troops killed a civilian in a vehicle after the driver failed to heed warnings to stop in Baqouba, 35 miles northeast of Baghdad.
In the statement, the military said a convoy was passing through a traffic intersection when the vehicle approached and failed to heed several warnings given by soldiers.
"Given the potential danger the vehicle presented to the convoy and the driver's repeated failure to respond to warnings, U.S. forces took action to disable the vehicle," the statement said.
An Iraqi police officer identified the dead man as 25-year-old Mohammed Qassim, but said he was the driver and not the passenger.
The officer, speaking on condition of anonymity because he was not authorized to speak to the media, said the driver appeared to be speeding and did not respond when the American soldiers issued warnings to stop.
Also on Tuesday, Iraqi police said a parked car bomb targeting an Iraqi army patrol exploded, killing one civilian and wounding six others.
The bomb exploded Tuesday night in the primarily Sunni neighborhood of Sadiyah in southwestern Baghdad, said a police officer. The officer spoke on condition of anonymity because he was not authorized to release information to news media.
Another Iraqi police officer, also speaking on condition of anonymity because he was not authorized to speak to the media, said a gunmen killed an Iraqi soldier in a drive-by shooting as he walked to his home in Riyad, north of Baghdad.