Late on Thursday, the chairman of Kenyatta's Jubilee party issued a statement alleging "massive subtle rigging" and claiming the "electoral process was highly compromised" after Ruto's party made a strong showing in an area where the dominant ethnicity is the same as Kenyatta.
The statement alleged voter intimidation, bribery, illegal displaying of campaign materials in polling station, mishandling of party agents and incorrect use of election materials. It provided no evidence and did not explain why the allegations had been made so late. Party officials were unreachable for comment.
As the Independent Electoral and Boundaries Commission [IEBC] officials verify and tally the results, Kenyan TV channels have been carrying out their own count, based on the forms, but stopped doing so on Thursday, with around a million votes left to go.
Executives from Citizen and Nation media groups said exhausted staff needed a rest.
"Now we have about a third of people working that we started with and we intend to pick up pace in the next few hours when the rest of the team come back," said Linus Kaikai, Director of Strategy at Citizen.
Stephen Gitagama, the CEO of Nation Media group, said his staff also needed a rest and that they focused on quality control. He referred Reuters to the election commission, known as the IEBC.
"IEBC bears the responsibility of providing the results, not the media," he said.
IEBC chairman Wafula Chebukati urged Kenyans not to worry about the different outcomes projected by various TV channels.
"There should be no panic about the differences we are seeing on the media screens," he said, adding that the official results would be released by the IEBC, which has to publish the outcome by August 16.
On Friday morning, the election commission had finally begun displaying an official count of presidential results on a board at the main tallying center. It had counted 1.5% of the vote.
Media tallies, which had nearly stopped by Friday morning, showed both leading candidates neck and neck, just under the 50% mark they needed to win. Less than a percent was divided between two other marginal candidates.
More than 99.7% of polling station results are in but thousands have not been counted by the media. The abrupt slowdown started when around 80% of the vote had been counted.
If no candidate wins more than 50% plus one vote, the two frontrunners will have a run-off.
Tuesday's election was largely peaceful but disputes over previous presidential votes have been followed by deadly violence, fueling jitters as provisional results point to a tight race between frontrunners William Ruto and Raila Odinga.
But with the complex process of verifying and tallying votes expected to take days, social media is swamped with disinformation about the results, with rights campaigners and civil society groups accusing both candidates' camps of sharing misleading posts.
No presidential poll outcome has gone uncontested in Kenya since 2002, and the disputes have led to bloodshed in the past, either involving ethnic clashes or police violence.
After 2017's presidential poll was annulled by the Supreme Court, citing irregularities and mismanagement by the IEBC, that election watchdog is under pressure to deliver a transparent vote and has uploaded forms to its website showing the results from each polling station.
This report was produced with information provided by Reuters and Agence France-Presse