Officials said a suicide car bomb went off at a checkpoint near Prime Minister Iyad Allawi’s party offices, located in the heavily fortified Green Zone.
At least 10 people are said to have been injured in the blast.
Supporters of militant leader Abu Musab al-Zarqawi claimed responsibility for the attack in a statement on an Islamist website.
On Sunday, Zarqawi – who tops Iraq’s most wanted list – apparently declared war on the election.
Insurgents have been staging regular attacks across the country as Iraq prepares for Sunday’s elections, making campaigning virtually impossible.