President Hamid Karzai widened his lead in Afghanistan's presidential race as new vote tallies were released Saturday, inching closer to the 50 percent threshold of votes he needs to avoid a run-off.

As Afghanistan's Independent Election Commission slowly releases partial results from the Aug. 20 presidential election, accusations of fraud have poured into the Electoral Complaint Commission. Videos of alleged fraud have been posted on the Internet, and Karzai's top challenger, Abdullah Abdullah, has made multiple complaints of cheating.

The allegations from Abdullah and other presidential candidates, along with low turnout in the violent south because of Taliban threats of violence, could strip the election of legitimacy in Afghan eyes. Security officials are monitoring tensions among Abdullah supporters for any signs that the election turmoil could ignite violence.

The latest results show Karzai ahead with 46.2 percent of the votes already counted against Abdullah's 31.4 percent. The results are based on 35 percent of the country's polling stations, meaning they could still change dramatically. Karzai must win 50 percent of ballots cast to avoid a runoff.

Final results will not be released until late September after the allegations of fraud have been investigated.

In Abdullah's latest salvo against the Afghan president, he said Karzai was behind "state-crafted, massive election fraud" and called his government "too corrupt" and the "worst in the world."

The U.N.-backed Electoral Comp might not be named until November or even later, and there are signs the strung-out process is fraying U.S.-Afghan relations.

On Friday, two officials said Karzai angrily accused the U.S. of pushing for a runoff vote during a heated meeting with Holbrooke the day after the election.

Karzai assured Holbrooke he would accept the election results but bristled when Holbrooke asked if he would also agree to a runoff, according to officials briefed about the meeting who spoke on condition of anonymity because of the sensitivity of the information.

An angry Karzai accused the U.S. of urging a second round before all votes had been counted. Karzai said he would accept the election commission's tabulation as long as it reflected the facts. He did not elaborate, according to the officials.

Karzai enjoyed close ties with the Bush administration, which helped propel him to power after the collapse of the Taliban government in the U.S.-led invasion.

Since the Obama administration took office, U.S. officials have accused Karzai of weak leadership as well as tolerating corruption and a flourishing drug trade.