Foreign observers have expressed confidence in Kenya’s electoral process, despite opposition leader Raila Odinga’s claim of massive fraud.
African observers described Tuesday’s poll as credible, while former US Secretary of State John Kerry said its integrity remained intact.
The European Union said candidates should accept losing as “natural”.
Mr Odinga alleges that results of the presidential poll have been rigged to give incumbent Uhuru Kenyatta victory.
On Wednesday, he said that the IT system of the Independent Electoral and Boundaries Commission (IEBC) had been hacked, and Kenya was witnessing the worst “voter theft” in its history.
The IEBC said there had been an attempt to hack its system, but it had failed.
Heading the Carter Center’s observer team, Mr Kerry urged all sides to wait for the final results, and for the loser to accept defeat.
He said there were “minor variances here and there”, but none that had so far made him doubt the poll’s integrity.
The “bottom-line” was that the IEBC had in place a “transparent process of voting, counting, reporting and securing the vote”, Mr Kerry added at a press conference in Kenya’s capital, Nairobi.
In a statement, the European Union observer mission said the opposition had made “serious allegations” and it was up to the IECB to complete the “remaining steps with maximum transparency and adherence to the law”.
“Candidates and their supporters must accept that not winning is a natural part of a democratic competition,” EU observer mission head Marietje Schaake said.
“Any irregularities or challenges to the process and outcomes should be addressed through petitions and the courts,” she added.
The IECB said it hoped to release final results from the presidential poll on Friday.
Raw polling data published on its website says that with almost all of results in, Mr Kenyatta – who is seeking a second term – is leading with about 54.3%, to Mr Odinga’s 44.8% share of the vote.
These suggest Mr Kenyatta is heading for a first-round victory.
Mr Odinga’s claim of rigging led to sporadic outbreaks of violence on Wednesday, but police denied reports that two people had been killed in election-related unrest.