Two armoured trucks carrying paramilitary police trundled into the centre of Zimbabwe's capital. Youths waving flags and shaking their fists gathered outside Mr Mugabe's ruling Zanu-PF headquarters at sunset to hear the 84-year old president make a last campaign speech.
Fears of poll violence were high after a survey in the official Herald newspaper predicted Mr Mugabe would get 56 per cent of votes in today's polls to win a sixth term in office.
His closest rival, Morgan Tsvangirai of the Movement for Democratic Change (MDC), will take 26 to 27 per cent of the vote, the survey by the University of Zimbabwe (UZ) political sciences department said, and former finance minister Simba Makoni less than 14 per cent.
A similar UZ poll correctly predicted the results of parliamentary polls in 2005. A private poll earlier this month gave the president only about a fifth of all votes.
Earlier, soldiers watched as youths backing Mr Tsvangirai and Mr Makoni rode trucks in the city centre, waving flags and chanting. There were long queues for bread, fuel and cash. Nearby, fresh graffiti read: "Zanu-PF is a thief".
The recent post-poll violence in Kenya that left 1,500 people dead is not far from anyone's mind. Zimbabweans pride themselves on being peaceful but eight years of economic turmoil, worsening shortages of basic foods and state oppression have worn tempers thin, at least in urban opposition strongholds, analysts say.
The authorities say the MDC plans to unleash mayhem if defeated. Yesterday ZBC radio, seen as the voice of the government, repeatedly played an old tape of Mr Tsvangirai saying: "If he (Mr Mugabe] won't go peacefully, we will remove him violently."
Hundreds of police recruits have been added to the force, state radio said. There are unconfirmed reports that the capital's 'prisons have been cleared to make way for post-poll arrests.
In a bustling Harare flea market, vendors were despondent. "We are not coming back until we have got rid of the old man," said Theo, a second-hand bookseller.
His colleague Minga predicted that Mr Mugabe would not accept defeat. "There's going to be trouble if Mudhara (the old man] loses. You know, the jongwe won't take it." Jongwe, cockerel in the local Shona language, is the symbol of Zanu-PF.
The election campaign has been largely peaceful. Mr Mugabe's opponents think this is because the president believes he has the results in the bag.
Mr Tsvangirai's campaign team says it has evidence of 8,000 ghost voters in Harare alone. There are also claims hundreds of names recently added to the voters' roll have addresses that are vacant plots.
"Mugabe has a time-tested bag of tricks that could frustrate the will of the people once again," wrote prominent newspaper publisher Trevor Ncube in the Zimbabwe Independent.
Mr Mugabe says all allegations of rigging are lies.
Voters have to pick a new president, parliament, senate and local government. The independent Zimbabwe Election Support Network says the authorities have deliberately skimped on the number of polling stations in opposition strongholds such as Harare.
In some areas, voters will have just nine seconds to cast four ballots – a near impossibility. There are fears thousands of voters may be turned away.
A local caf owner said he was heading for England. "I'm out of here before the rocks start flying," he said.
DECISION DAY FOR ELECTORATE
SOME 5.9 million people are registered to vote today.
About 9,000 polling stations will be open for 12 hours, during which voters will decide a president, 210 parliament seats, 60 senate seats and 1,600 local council seats. Voter turn-out in the 2005 parliamentary polls was about 65 per cent. If no presidential candidate wins 51 per cent or more of the vote, there will be a run-off.
The candidates are: Robert Mugabe, the current president; Morgan Tsvangirai of the Movement for Democratic Change, a former trade union leader; and Simba Makoni, a former ruling party loyalist and finance minister who is running as an independent.