As the count continues, former Honduran president Juan Orlando Hernandez of the National Party was released from a US prison on Monday, where he was serving a 45-year prison sentence for drug trafficking and firearms charges, a Federal Bureau of Prisons registry showed.
His release came after US President Donald Trump urged Honduran voters to cast their ballots for the National Party candidate Asfura and said he would pardon Hernandez.
A White House official confirmed on Tuesday that Trump had pardoned Hernandez.
The preliminary results released on Monday show Asfura and Nasralla of the Liberal Party each holding just under 40 per cent of the vote, with Asfura only 515 votes ahead.
Rixi Moncada, of the ruling LIBRE Party, was well behind in third with 19 per cent of the vote.
With the razor thin margin, the electoral body declared the race a "technical tie".
Ana Paola Hall, the body's president, called for calm and patience as electoral workers moved into the slower stage of verifying the vote tallies by hand.
The preliminary results are based on tallies digitally transmitted by polling stations across the country.
Trump weighed in on Monday in a social media post in which he suggested Honduras was "trying to change the results of their Presidential Election".
"If they do there will be hell to pay! The people of Honduras voted in overwhelming numbers on November 30th," Trump said on his Truth Social platform.
There was high voter turnout in Sunday's election, which was peaceful across the country, according to the Organisation of American States, which observed the vote.
It said in a statement on Monday that it "was able to verify that the voting proceeded normally, except for isolated incidents in some municipalities of the country".
But there are concerns that if the vote count drags on, the highly charged election environment could lead to protests and possible violence.
On Monday, problems with the online portal where results were meant to be updated added to frustration around the vote.
The website was down for long stretches, with local media and politicians criticising the outage.
The electoral body recognised the issues in a statement on Tuesday and said the company responsible for the system had informed it that problems meant some ballots had still not been processed.
CNE, as the electoral authority is called, said it would now release information about the count directly to media and political parties to ensure the public was able to follow the results.
Former president Manuel Zelaya, who is also the husband of current President Xiomara Castro, lambasted Trump's interference in the election, saying on X that it was an attempt to stop Moncada's bid, and vowing the Honduran people would stand up for democracy.
"We who fight for liberty are on our feet," he wrote.
"We are patriots and nobody yields."
On Monday evening, Moncada said the elections were "still not lost" and alleged that the other parties had manipulated the process.
She also denounced US interference in the election.
In the run-up, Trump threw his support behind Asfura, 67-year-old former mayor of Tegucigalpa, in a series of social media posts, saying he could work with him to counter drug trafficking.
He accused Moncada of being a "communist".
