Sunni candidate Muthana al-Jourani was meeting supporters in Baquba at the time of the attack, the BBC reported.
After tossing a grenade into the meeting, the suicide bomber blew himself up, police said.
No group immediately claimed responsibility for the attack.
Provincial elections are scheduled for April 20, the first in Iraq since 2010.
LGBT community has 'bullied the American people': Bachmann
McPhee, Cokas 'working on their marriage' after affair