KABUL, Afghanistan — A vice presidential running mate of interim Afghan President Hamid Karzai survived an assassination attempt Wednesday when a roadside bomb exploded as his convoy passed.

The attack on the last day of campaigning before Saturday's first direct presidential election killed one man and injured five others, said Fazel Ahmad Nazari, chief of the provincial criminal department. Among the injured: the former provincial governor. It was the latest indication there could be violent attempts to disrupt the vote.

Seventeen candidates are on the ballot with Karzai, although two said Wednesday that they were dropping out. The interim president, who also has faced assassination attempts, spoke at a rally in Kabul on Wednesday, one of his few public campaign appearances.

The vice presidential running mate targeted by the blast in Badakhshan Province was Ahmed Zia Masood, the younger brother of Ahmad Shah Masood. The elder Masood was a legendary resistance fighter for the Northern Alliance who was assassinated by al-Qaeda operatives two days before Sept. 11. Ahmed Zia Masood was on his way from the airport to a rally when the bomb exploded. He wasn't injured.

“We're doing an investigation right now, and we're trying to find out who was behind it and get them apprehended,” said Khaleeq Ahmad, a Karzai spokesman.

Reuters reported that the Taliban, the former Islamic fundamentalist regime ousted nearly three years ago, claimed responsibility.

Ahmad said that the rally in Faizabad, the provincial capital, was canceled, but the vice presidential candidate met with village elders.

Karzai, who called the attack “dastardly,” picked up three key endorsements as campaigning officially ended to allow two days of preparation for the election.

The two minor presidential hopefuls who dropped out, ethnic Tajik Abdul Hasid Aryan and Pashtun candidate Sayed Ishaq Gilani, backed Karzai. The interim president, a Pashtun, has portrayed himself as someone who can unite the country's largely tribal society.