Officials said the attacker struck as Sunni candidate Muthana al-Jourani was meeting supporters in Baquba, 60km (35 miles) north-east of Baghdad, the BBC reported. No group has claimed responsibility for the deadly attack.
According to NDTV supporters of the Azimun Ala al-Bina party, a small local list, had been gathered at around lunchtime in the city of Baquba when a militant threw a grenade before a suicide bomber then blew himself up.
A police colonel and a medic at Baquba hospital said at least 25 people were killed and 60 others were wounded.