Abdullah said he was "certain" of carrying the second round, thanks to the wide cushion his first-round results give him, as well as endorsements he's won from several of the smaller first round candidates, including third-place finisher Zalmai Rassoul — who was considered Karzai's candidate of choice.
But it's unclear whether Rassoul can deliver the votes of his supporters, who are largely Pashtuns, the country's largest ethnic group.
Over 7 million Afghans voted in the first round, considered a strong turnout in an election plagued by Taliban threats and logistical hardships for both voters and poll workers.
U.S. representative James Dobbins expressed the hope that a successful election would be a step toward enticing the Taliban to agree to talks.
"We're hopeful that the Taliban will reconsider their position and be willing to engage directly with us possibly, but even more importantly, directly with the Afghan government," Dobbins said at a meeting in Tokyo of the International Contact Group for Afghanistan and Pakistan.
The head of the United Nations mission in Afghanistan commended the candidates for running "a hard-fought but positive campaign."
"I hope that the prevailing respectful tone seen in the first round is preserved in the weeks ahead," said Jan Kubis, the U.N. secretary general's special representative for Afghanistan. "Candidates have a responsibility to call on their supporters to refrain from inflammatory rhetoric, intimidation, and threats."
Associated Press writers Amir Shah in Kabul and Ken Moritsugu in Tokyo contributed to this report.
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