KABUL, Afghanistan -- Afghans braved threats of violence and searing heat Saturday to vote in a presidential runoff that likely will mark the country's first peaceful transfer of authority, an important step toward democracy as foreign combat troops leave.
The new leader will be challenged with trying to improve ties with the West and combatting corruption while facing a powerful Taliban insurgency and declining international aid.
Abdullah Abdullah, who emerged as the front-runner with 45 percent of the vote in the first round, faced Ashraf Ghani Ahmadzai, an ex-World Bank official and finance minister. Neither garnered the majority needed to win outright, but previous candidates and their supporters have since offered endorsements to each, making the final outcome unpredictable.
The two men differ more in personality than policy. Both promise to sign a long-delayed security pact with the United States, which President Hamid Karzai has rebuffed. That would allow nearly 10,000 American troops to remain in the country for two more years to conduct counterterrorism operations and continue training and advising the ill-prepared Afghan army and police. And both pledge to fight for peace and against corruption.
But their different ethnic backgrounds have highlighted the tribal fault lines in this country of 30 million ravaged by decades of war.
The White House praised Afghan voters for their "courage and resolve" in the second round.
Observer groups said the balloting was relatively smooth, although both candidates and observers said they had evidence of fraud ranging from ballot box stuffing to proxy voting. Several polling stations also opened late or failed to open at all because of security concerns, and many voters complained of ballot shortages.
Independent Election Commission chairman Ahmad Yousuf Nouristani, speaking at a joint news conference after polls closed, said initial estimates show that more than 7 million Afghans voted, which would be equivalent to the first round on April 5. That would be a turnout of about 60 percent of Afghanistan's 12 million eligible voters.
Official preliminary results were to be announced July 2, with final results released July 22.
Mr. Nouristani said his commission would release partial results in the coming weeks.