Kenya’s presidential election, beset by technical glitches and vote-tallying delays, was thrown into more disarray Thursday after the party of one of the top contenders alleged that preliminary results were fraudulent and called for the vote count to be halted.

The allegations by Prime Minister Raila Odinga’s party come as his main rival, Deputy Prime Minister Uhuru Kenyatta, is leading the race by 53 percent to 41 percent, with about half of the votes counted.

“We have evidence that results we have been receiving have actually been doctored,” Kalonzo Musyoka, Odinga’s running mate, told reporters Thursday in the capital, Nairobi. “The national vote tallying process lacks integrity and has to be stopped.”

After the previous presidential election in 2007, Odinga made similar accusations that he was cheated of victory, triggering ethnically charged chaos that left more than 1,000 Kenyans dead and several hundred thousand homeless. The violence devastated Kenya’s economy and its image as a bulwark of stability on the continent.

Musyoka added Thursday that his comments were not a call for Odinga’s supporters to wage mass action, and he urged them to remain calm.

In Nairobi and other parts of the nation, the streets were quiet following Musyoka’s remarks. In interviews, many Kenyans said they would accept the results or challenge them through the courts rather than plunge their country into mayhem. Still, as each day passes without a result, many observers fear that tensions and anxiety could rise among rival tribes, raising the specter of another eruption of ethnic violence.

Musyoka listed several voting districts where he claimed that the number of votes cast exceeded the number of registered voters. He also questioned why on Tuesday there were more than 300,000 rejected ballots, which, if counted, could have narrowed the gap between Odinga and Kenyatta, leading to a possible runoff.

But on Thursday, the vote tallies showed a sharp fall in the rejected votes, raising questions about what happened to them. Musyoka added that Odinga’s party could seek a court injunction to stop the vote count.

Kenyan election officials said their findings did not support Musyoka’s allegations.

“With the rigorous verification in place, there is no room to doctor the results whatsoever by any election official,” Isaak Hassan, chairman of the Independent Electoral and Boundaries Commission, told reporters. “We cannot stop tallying. This is a legal process.”

International election observers have declared the election transparent, despite the technical problems, anchored by a breakdown in the computer system that was electronically tallying the votes. That has forced election workers to manually count the votes, which has dramatically slowed down the process.

If no candidate wins by 50 percent — there are a total of eight presidential candidates — a runoff vote between the top two candidates, Kenyatta and Odinga, is scheduled for April, provided there are no legal challenges.

The counting could conclude Friday, but it could also drag into Monday, the last day that the results must be declared, according to Kenyan law, said Hassan.

The United States and its allies are closely observing the results. Kenya is a key counterterrorism ally, playing an important role in containing Somalia’s al-Qaeda-linked al-Shabab militia. It is also an economic powerhouse in the region, vital to stability in East Africa.

A Kenyatta win would bring more challenges for the United States and Western powers. Kenyatta and his running mate, William Ruto, are accused of crimes against humanity by the International Criminal Court and are scheduled to face trial. On Thursday, the ICC announced that it would postpone the trial, originally set for next month, to July 9.

Both men are charged with instigating tribal mobs to rampage and shed blood after the 2007 vote. They have denied the allegations and said they would cooperate with the court.

Kenyatta has accused Western countries, particularly former colonial power Britain, of interfering in the vote. Britain’s high commissioner to Kenya has called the charges “entirely false and misleading.”