Zimbabwe President Robert Mugabe branded the United States "absolutely insane" on Thursday for voicing concerns about a 31 July election, although neighbouring South Africa joined Washington in criticising chaotic preparations for the vote.
Speaking to thousands of supporters in Chinhoyi, 115km northwest of Harare, the 89-year-old also rejected calls for reform of partisan security forces, saying his main rival, Prime Minister Morgan Tsvangirai, could make changes if he won.
"In America they are saying Zimbabwe has gone for an early election without reforms. Americans must be mad and absolutely insane," Mugabe said in an address that last more than 2-1/2 hours, confounding speculation his health is failing.
The vote is meant to end five years of fractious unity government under a deal brokered by regional power South Africa following violent and disputed polls in 2008 but with its credibility already being questioned, those hopes are waning.
The United States said this week it was deeply concerned by a lack of transparency, suggesting Washington was in no mood to ease sanctions against a victorious Mugabe even if he wins without violence.
Tellingly, it is not just Mugabe's long-time foes in the West rounding on the continent's oldest head of state, who has run the southern African nation since independence from Britain in 1980.
In unusually strong criticism, South African President Jacob Zuma's top Zimbabwe expert, Lindiwe Zulu, said Zuma had telephoned Mugabe to tell him he was "not pleased" with the run-up to the poll.
"We are concerned because things on the ground are not looking good," Zulu told Reuters.
South Africa wants to avoid a repeat of the 2008 violence, which brought a flood of refugees into the country and added a further burden on stretched state finances.
Mugabe called the election on 31 July in compliance with a Constitutional Court order but the move was criticised by his opponents and Pretoria as too soon to allow proper preparations.
Zulu's comments are likely to infuriate Mugabe, who labelled her "stupid and idiotic" at a rally this month after she called for a delay of a few weeks to ensure the process runs as smoothly as possible.
Advance voting for 70 000 police officers and soldiers on Sunday and Monday compounded fears of a chaotic poll, raising the prospect of a disputed result and civil unrest in a country with a history of election violence.
In the special voting, long lines formed at polling stations and some people were unable to vote because ballot papers did not turn up at all - one of several logistical challenges acknowledged by the Election Commission.
Pretoria's verdict on the quality of the vote has added significance because election observers from the European Union and United States are barred from entering Zimbabwe.
There have been no formal opinion polls but most analysts see Mugabe's Zanu-PF as the favourite given its monopoly of state media and the problems with voter registration encountered by many young, urban Zimbabweans - Tsvangirai's support base.
Britain has also said its misgivings about the election justified maintaining European Union sanctions imposed more than a decade ago for suspected vote-rigging and human rights abuses.
"We are concerned that a number of important electoral and other important democratic reforms have not been completed," a Foreign Office spokesperson said.
While sanctions remain in place, Zimbabwe has no chance of rescheduling billions of dollars of defaulted World Bank and IMF debt, leaving it unable to access the multilateral credit needed to rebuild its economy.
Britain's former Africa minister, Peter Hain, said Mugabe's methods had changed from 2008, when at least 200 people, almost all of them Tsvangirai supporters, were killed, but that the entrenched president's disdain for a free and fair vote had not.
"In the past, he's relied more on brute force and violence. This time it's all sorts of double-deeds," Hain told Reuters. "It will be very hard for sanctions to be lifted if the outcome is as it looks to be - namely an election by bribery and constitutional chicanery."