Kabul, Afghanistan ? Afghanistan’s president said Sunday he is optimistic that next month’s legislative elections will be peaceful, but ongoing pre-vote violence left one candidate dead and three American troops wounded.

Hamid Karzai’s comments followed a major offensive by U.S.-led coalition and Afghan troops against militants intent on subverting the Sept. 18 polls. The operation has left hundreds of suspected rebels dead.

“We are very sure the election will take place peacefully,” Karzai told reporters in Kabul. “There will be threats … but that would not deter the Afghan people from participating. We will soon have a parliament.”

But other Afghan officials, as well as U.S. authorities, have warned that the violence may worsen ahead of the elections, the next key step toward democracy after a quarter century of fighting.

American military commanders have prepared elaborate security plans to safeguard the voting, saying Taliban rebels are throwing all their resources into disrupting the polls.

In the latest anti-American violence, militants attacked a U.S. military convoy on Friday 25 miles east of Kabul, wounding three American soldiers, a U.S. military statement said. An attack helicopter rushed to the site, but the rebels had fled.

The wounded were in stable condition after being evacuated to Bagram, the main U.S. base in Afghanistan, about an hour’s drive north of Kabul, it said.

Attacks on the U.S. military so close to Kabul are rare and Friday’s assault occurred less than a week after a roadside bomb in the capital exploded near a convoy of U.S. Embassy vehicles, wounding two American staff members.

In southern Uruzgan province on Sunday, gunmen ambushed a parliamentary candidate, Adiq Ullah, as he was driving, killing him and wounding two others in his vehicle, said provincial Gov. Jan Mohammed Khan.

He blamed the Taliban for the killing. Security forces pursued the insurgents, but they escaped, the governor said.

Ullah’s killing brings to four the number of candidates killed so far in the lead-up to the polls. Four election workers also have been murdered and several election offices have been rocketed.

Meanwhile, Karzai and visiting Indian Prime Minister Manmohan Singh called for a regional effort to fight terrorism, saying only with the help of Pakistan can the threat of further militancy be defeated.

“India, Pakistan, Afghanistan … need to join hands and work very strongly for the safety and security of all people in the three countries,” Karzai said.

Singh, the first Indian leader to visit Kabul in 29 years, said, “We have an obligation to work together to deal with this madness.”

Security forces in both India and Afghanistan are battling Islamic militants who are allegedly backed by Pakistan, which lies between them.

Indian officials claim Islamabad channels aid to militants in Indian-controlled Kashmir, while Afghan officials allege Pakistan is helping Taliban insurgents here. Pakistan’s government denies both charges.

Karzai said there “has been cooperation from Pakistan in the anti-terrorism drive,” but he called for ties between Islamabad and Kabul to be strengthened in the hope that Pakistani leaders can be persuaded to do more.