A suicide attacker has killed 13 people and injured more than 30 at an election rally in Nangarhar province - the first major attack on campaigning since it began last Friday.
Supporters of parliamentary candidate Abdel Naser Momand had gathered in Kama district when the blast happened.
The parliamentary election will be held on 20 October and there have been threats of violence.
Both the Taliban and the Islamic State group have urged a boycott of the vote.
Provincial governor Ataullah Khogyani told AFP that Mr Momand had survived the attack, but did not say if he was injured.
The force of the blast reportedly caused the ceiling to collapse on the crowd of about 250 people.
There was no immediate claim of responsibility for the attack.
Recent reports suggest this has been the deadliest year in Afghanistan since the 2001 US-led invasion, with around 20,000 people - civilians and combatants - thought to have been killed.
The run-up to the vote has seen an increase in violence, with militants vowing to disrupt it.
More than 2,500 candidates are reportedly standing in the election.