The finance ministry said it needs to resolve a shortfall of about $85-million, as a month-long chaotic voter registration effort drew to a close on Tuesday.
Tendai Biti, the outspoken finance minister, described preparations for the July 31 polls as "a nightmare".
"We don't have money for these elections, and everyone knows it. It's a horror movie except that you are not watching the movie, you are part of it," Biti said late on Monday.
The elections are the first to be held since the violent 2008 polls forced President Robert Mugabe to join into a coalition government with longtime opposition leader Morgan Tsvangirai, a bitter political nemesis. Mugabe has ruled Zimbabwe since independence in 1980.
On Tuesday, Mugabe's office said it was cancelling Cabinet meetings until the vote so that ministers can campaign for the election.
Tsvangirai (61) began intense campaigning in the remote north-east on Tuesday. Mugabe (89) has not announced his own campaign schedule but his Vice-President Joice Mujuru (58) has begun a series of rallies for their Zanu-PF party.
Mugabe's opponents maintained he had acted alone without consulting coalition leaders in a ploy to favour his party. The Zimbabwean president said he was following the instructions of a Constitutional Court ruling in May.
The rushed election
Tsvangirai had argued that the July 31 date did not allow enough time for the needed democratic reforms to take place, and that the rushed election did not provide the conditions necessary for a free and fair vote. He later said he was accepting the date with sadness and reluctance but was confident of a victory over Mugabe.
National elections in Zimbabwe are routinely held over two days with ballots cast at up to 9 000 polling stations across the country, slightly larger than Germany. The commission says tens of thousands of voters who have since died have been removed from the lists.
The US-based Robert F Kennedy Centre for Justice and Human Rights said in its latest report on Zimbabwe that the close approach of the vote has ramped up political tensions in the country. It said opponents of Mugabe are facing "an atmosphere of intimidation", curbs on free expression and political activities, and the suppression of easily accessible voter registration and voter education.
"This behaviour is unacceptable and represents clear breaches of domestic and international law," said Santiago Canton, head of the centre's rights group.
Leaders of the 15-nation regional bloc known as the Southern African Development Community, or SADC, had also called on Mugabe and the judiciary he controls to delay the crucial elections.
Mugabe, launching his party's manifesto on Friday, had also threatened to withdraw from SADC, the regional bloc he helped found, saying its chief mediator on Zimbabwe, South African President Jacob Zuma, and his colleagues had pushed for delaying the polls.
Biti, the finance minister, said he has had to "freeze" payments to government departments and only meet public service salaries to try to find the money for this month's vote.
"The whole thing is an absolute, undiluted dog's breakfast," Biti said. – Sapa-AP