Al-Haydari was shot
during an ambush on his car in the Iraqi capital Baghdad.
Spokesman Scott McClellan said the U.S. government condemned in the strongest terms al-Haydari's assassination.
McClellan said despite the killing, the situation in much of Iraq is secure enough to move forward with holding elections, though he conceded there were "a few areas we're continuing to work to improve the security situation."
McClellan also said that U.S. President George W. Bush had spoken with Iraqi interim Prime Minister Iyad Allawi and that the two leaders did not discuss any postponement of the elections.
Iraqi Foreign Minister Hoshyar al-Zebari also said yesterday that elections will be held on schedule.
In the past few days, Iraq's interim president and defense minister have suggested that the poll might be delayed until the security situation improves and that Sunni groups that have vowed to boycott the national election could be persuaded to participate.
Earlier today, at least 10 people were killed and 56 wounded in a suicide truck bombing outside the Green Zone that houses U.S. and Iraqi officials in Baghdad.
Five U.S. troops were killed in separate incidents today in Iraq.