The candidate, Saleh Mohammad Achekzai, was holding a meeting at the time of the attack, which also killed several of his bodyguards, Attahullah Afghan, head of the southern Helmand provincial council told The Associated Press in a telephone interview.
Achekzai's home was in Lashkar Gah, the capital of Helmand province, where the Taliban are said to control nearly 80 percent of the area. In recent months the insurgents have on occasion laid siege to the city.
The attack on Achekzai comes a day after the Taliban issued a statement condemning the polls and warning candidates and Afghan Security Forces that they would be targets if they participate in the elections. The Taliban called the polls a U.S.-manipulated event to further their hold on the country.
No one immediately took responsibility for the attack, which is not the first since campaigning began on Sept. 28. A suicide bomber struck an election rally in Afghanistan's eastern Nangarhar province last week, killing at least 14 people and wounding around 40, according to government officials.
There are 2,565 candidates vying for seats in the 249-member chamber, including 417 women candidates. In the run-up to campaigning, five candidates have been killed in separate attacks. Officials from the country's Independent Election Commission said another two candidates have been abducted, with their fates unknown, and three others have been wounded in attacks. Afghan security forces accidentally killed three bodyguards of an independent candidate during a raid on a house near his residence in the eastern Kunar province on Sunday.
In other violence in Afghanistan, 15 Afghan Security Force personnel were killed in separate attacks on Monday. Gen. Faqir Mohammad Jawzjani, provincial police chief in Jawzjan, told The Associated Press on Tuesday that an attack that took place in Qush Typa district late on Monday killed 12 security personnel and wounded another 10.
Jawzjani says the assault was a failed attempt to capture the district. He said 30 Taliban were killed and 19 wounded. Spokesman Zabihullah Mujahid said the Taliban claimed responsibility for the attack. He, however, claimed a higher number of casualties among Afghan police. The Taliban often exaggerate their claims.
Also on Monday, the Taliban attacked a district in southern Ghazni province, killing three members of the security forces. Police Chief Farid Mashal said five were wounded.
Associated Press writer Abdul Khaliq in Lashkar Gah, Afghanistan contributed to this report.