Venezuela's electoral authorities say preliminary results of an audit of the vote on President Hugo Chavez's rule show there was no fraud.
The review is being carried out by the official electoral authority and international observers
They say more than 30% of 150 randomly chosen polling sites have been checked so far - confirming the outcome of the vote there.
The opposition has refused to take part in the review of Sunday's poll, which Mr Chavez officially won.
International election monitors have endorsed the result.
The outcome of the audit is expected to be published at the weekend.
The audit is being carried out by the official electoral authority - the Venezuelan National Electoral Council - and international observers from the Carter Center and the Organization of American States (OAS).
They were due to visit 150 polling sites, checking the results produced by voting machines against paper records, in the presence of government and opposition representatives.
The Venezuelan opposition is crying foul
However, the main opposition parties have refused to send representatives, saying the review would not properly investigate their allegations of massive fraud in the vote.
They are calling for checks to include touch-screen voting machines, saying many were rigged - allegations rejected by electoral officials.
A senior member of the opposition, Nelson Rampersad, told journalists that many machines stopped recording votes against Mr Chavez once a ceiling had been reached.
Mr Chavez, whose populist policies have split Venezuelan opinion, officially won the poll with 59% of the vote.
'No reason for doubt'
Announcing the audit on Tuesday, former US President Jimmy Carter said he and the OAS had suggested the move to allay fears over the validity of the outcome.
He stressed that he himself had "no reason to doubt the integrity of the electoral process or the accuracy of the referendum itself".
Mr Chavez has urged the opposition to have the "grace" to accept the result and called for national reconciliation.
Carter is a veteran election observer
And some opposition figures have begun saying the referendum result should be accepted.
"We have to bite the dust of defeat," Manuel Rosales, governor of Zulia state, was quoted as saying by the Associated Press news agency.
The head of the country's biggest business association, Fedecameras, has also called for reconciliation between Chavez supporters and opponents.
The opposition has fought a tireless campaign to see Mr Chavez ousted. The president survived a short-lived coup in April 2002 and a two-month strike that badly damaged the economy later that year.
The referendum was activated after the opposition collected signatures from 20% of the population - a recall mechanism inserted into the Venezuelan constitution by Mr Chavez in 1999.