President Hamid Karzai's main challenger backed off a boycott of Afghanistan's landmark election over allegations of fraud, saying Monday that he would accept the formation of an independent commission to look into any irregularities in the vote.

The announcement by Yonus Qanooni, an ethnic Tajik candidate, followed similar statements Sunday by Masooda Jalal, the only female presidential hopeful, and Mohammed Mohaqeq, an ethnic Hazara candidate.

"I don't want to be against the election, and I appreciate the good will of the people of Afghanistan," Qanooni said. "I want to prove to the people of Afghanistan that the national interest is my highest interest."

He said he made his decision after a meeting with U.N. special representative Jean Arnault and U.S. Ambassador Zalmay Khalilzad.

Abdul Sattar Sirat, an Uzbek candidate who rallied the others to support the boycott, also appeared to back down. His spokesman, Ramatullah Jalili, said Sirat would respect the decision of an independent electoral commission.

The announcements were a victory for election organizers, who agreed to set up the panel Sunday to end the boycott declared by all 15 opposition candidates in the middle of Saturday's voting. Their complaint focused on allegations that the ink used to mark voters' thumbs in some polling stations could be rubbed off, allowing some people to vote more than once.

The election has been hailed as a success by U.N. officials, President Bush and other world leaders. International electoral observers have criticized the 15, saying their demand to nullify the vote was unjustified.

German Chancellor Gerhard Schroeder, the first foreign leader to visit Afghanistan since Saturday's election, all but declared Karzai the winner before a single ballot was counted. Schroeder said the poll "was a great step toward democracy and stability" and predicted a Karzai win.

"It is my opinion that he will do it, and in the first round," the German leader said.

Officials praised the high voter turnout in Afghanistan, which has never before held a presidential election. Voters went to the polls despite fears of attacks by Taliban guerrillas, which failed to occur.

"The numbers and enthusiasm both were very, very great," Karzai said Monday on NBC's "Today" show. "People braved attacks by terrorists and went to the election."

Boxes of ballots, some arriving by mule, were not expected to finish reaching counting centers until Tuesday at the earliest. About 10.5 million voters were registered for the election.

Before the tallying can start, the number of ballots in each box will be checked against a list of votes cast to ensure the boxes have not been stuffed with fraudulent votes, U.N. officials said. Then the ballots from various districts will be mixed together so no one knows which area favored which candidate.

Counting may not start until Wednesday or Thursday, said an electoral spokesman, Sultan Baheen. Another electoral spokesman said candidates had until Tuesday evening to file formal complaints and that the commission did not want to start the count until after it had reviewed them.

Final results were not expected until the end of October.

Candidate Yonus Qanooni, the former interior minister, told reporters at his home that he was putting national interests above his own.