Afghanistan's election commission Tuesday ordered a Nov. 7 runoff in the disputed presidential poll after a U.N.-led investigation voided thousands of fraudulent ballots, dropping incumbent Hamid Karzai's votes below 50 percent of the total.

Karzai accepted the ruling by the commission "legitimate, legal and constitutional," agreeing to a second round vote.

SLIDESHOW: Presidential Runoff Ordered

The announcement came two months to the day after the first round vote and follows weeks of political uncertainty at a time when Taliban strength is growing.

The chairman of the Independent Election Commission, Azizullah Lodin, said the commission, which organized the Aug. 20 vote, did not want to "leave the people of Afghanistan in uncertainty" any longer.

"The commission is agreed to go to a second round and say that nobody got more than 50 percent," Lodin said. Afghan electoral law says a runoff is needed if no candidate gets above that percentage.

LIVESHOTS: Afghan Election Panel Throws Out Ballots

Lodin said all the materials are ready for the Nov. 7 runoff.

Karzai announced his acceptance of the findings at a press conference alongside U.S. Sen. John Kerry and Kai Eide, the head of the U.N. mission in Afghanistan. Kerry said the agreement on a second round had transformed the crisis into a "moment of great opportunity."

Kerry said Karzai "has shown genuine leadership in the decision he has made today."

The decision to accept the fraud findings and move to a run-off showed that Afghanistan "recommits to the democratic process." He complimented Karzai for his "openness to finding ways of resolving differences."

"The international community is 100 percent committed to helping to carry out this election," Kerry said.

The possibility of a runoff emerged Monday after a U.N.-backed panel threw out a third of Karzai's votes from the Aug. 20 ballot, pushing his totals below the 50 percent threshold needed for a first round victory and setting the stage for a run-off against former Foreign Minister Abdullah Abdullah.

Another election risks the same fraud that derailed the August vote, along with inciting violence and increasing ethnic divisions. A November runoff also could be hampered by winter snows that block off much of the country starting mid-month.

The primary alternative that has been floated is a power-sharing deal, though the form that could take is unclear. And it could take weeks or months to hammer out an agreement between the two rivals.

So, the United States is still far from finding a government it can point to as a legitimate partner in the increasingly violent battle against the Taliban.

In the latest fighting, Afghan and international forces killed about half a dozen militants during a raid on compounds used by a Taliban commander in eastern Wardak province on Tuesday, the U.S. military said in a statement.

A spokesman for the Abdullah campaign said earlier they do not consider a coalition or power-sharing government an acceptable alternative.

"A coalition is against the law and does not benefit the political process of the country," Fazel Sancharaki said, noting that Afghan electoral law has no provisions for such a process.

"If anyone proposes that, they should have very strong reasons for it." He did not elaborate on what reasons might persuade Abdullah to consider such an option.

Abdullah still sees a second-round vote as the best path, he said. If there are security or weather concerns that mean a runoff can't be held before spring, some sort of interim administration should need to be worked out between the two candidates and with the help of the international community, Sancharaki said.

"Karzai's term is over, we cannot accept him for several more months," he said.

The agreement that a runoff is required is likely just the first step in negotiations to iron out these differences between the Karzai and Abdullah camps.

The U.S. appears to be backing a power-sharing deal, but there are a number of possible scenarios. In Afghanistan, many have also suggested holding a loya jirga — a traditional Afghan meeting where decisions are made through a combination of negotiation and consensus.

American officials have repeatedly said they're pushing for a "legitimate government" in Afghanistan, which does not necessarily need to be elected. People familiar with the talks have said both Karzai and Abdullah have said privately that they're open to the idea of a coalition, though with very different interpretations of what that would mean and when it could happen.

The Aug. 20 poll was characterized by Taliban attacks on polling stations and government buildings that killed dozens of people. In some areas, militants cut off the ink-marked fingers of people who had voted.

Turnout was dampened during that vote because of threats of violence from the Taliban and many say even fewer people would come out in a runoff.

Despite the danger, some Afghans in the southern city of Kandahar — a Karzai stronghold where many votes ended up thrown out for fraud — said they would prefer a runoff to a coalition government. Karzai is widely expected to prevail in a runoff vote.

Abdur Rahman, who runs a foreign exchange bureau in Kandahar, said a runoff would be difficult, but if there is no other option, the government should organize one.

"We support a runoff, but a new coalition government would not be good for Afghanistan," said 46-year-old Rahman, who voted for Karzai. "Karzai already has a coalition. Why would he make any deal with Abdullah or give him power?"

The Associated Press contributed to this report.