Eager to vote, Zimbabweans began lining up before dawn Saturday for elections that present President Robert Mugabe with the toughest political challenge of his 28 years in power. The opposition accuses Mugabe of plotting to steal the election. Tensions rose Friday, with soldiers and police in a convoy of armored personnel carriers and water cannon patrolling through downtown Harare, the capital, and the security chiefs warning against violence. Police presence at the polls Saturday was heavy. The economic collapse of what was once the region's breadbasket has been a central campaign issue, with the opposition accusing Mugabe of misrule and dictatorship. Mugabe, appealing to national pride, blames the West - and charges his opponents are stooges former colonial ruler Britain. In southern Bulawayo, the second city, Moreblessing Ndlovu said he chose democracy over dictatorship. "The people of Zimbabwe have had enough of this dictatorship," said Ndlovu, his bare feet reflecting his poverty. "Everyone here is hungry. They want to see a change," he said pointing a snaking line of about 200 people waiting to vote. Some got in line hours before the scheduled 7 a.m. (0500GMT) opening. "The message is very clear: We want to see change in this country," said Moffat Simon Mabhena, a 78-year-old retiree voting in Bulawayo, an opposition stronghold. "I have been here since 2:30 am and it's because I want to see Robert Mugabe out." Running against Mugabe are opposition leader Morgan Tsvangirai, 55, who narrowly lost disputed 2002 elections, and former ruling party loyalist and finance minister Simba Makoni, 58. Makoni has shaken up Zimbabwe's politics with his appeal to disillusioned citizens, threatening to take votes from both the opposition and the ruling party. All three candidates voted early Saturday, with Mugabe telling reporters afterward he would accept whatever results emerged and rejecting opposition charges he had already orchestrated his own victory. "We are not in the habit of cheating," he said. "We don't rig elections." Tsvangirai sounded a resolute note, saying: "The people's victory is assured." Most stations opened after 7 a.m. and people complained the process was slow. But Noel Kututwa, head of the independent Zimbabwe Election Support Network, said voting was going smoothly countrywide. "It looks like a large turnout so far, and there is some excitement in the air," he said. His group's monitors reported a heavy police presence at polling stations, allowed under a belated presidential decree that breaks an agreement signed with the opposition. Some fear it could frighten away opposition voters. There are 9,000 polling stations for 5.9 million voters. Independent democracy watchdogs have complained there were too few stations in urban opposition strongholds, and that they have seen the names of dead of fictitious people on the official voting list, presenting an opportunity for fraud. Zimbabweans are voting in a single day for the first time for president, 210 legislators, 60 senators and 1,600 local councilors. Polls are scheduled to close at 7 p.m. (1700 GMT, 1300 EDT) and preliminary results are expected by Monday. Mugabe told a final rally Friday that Saturday's vote would show Zimbabweans' opposition to colonialism. "Zimbabweans are making a statement against the meddling British establishment," he said. Mugabe called for discipline at the polls despite "provocation from outsiders who are already claiming the elections are not free and fair." US State Department spokesman Sean McCormack said Friday, "There are a lot of big question marks hanging over this election in terms of the integrity of the electoral process." Friday night, monitors from the 14-nation Southern African Development Community said they had observed "a number of matters of concern," which they did not identify. Zimbabwe has barred observers traveling from the United States and the European Union, but the US State Department said it had 10 people from its embassy in Harare monitoring the elections. Tsvangirai on Friday urged supporters to stay at polling stations until counting began, to help prevent rigging, and he appealed to public servants not to participate in fraud. Mugabe blames Britain and Western sanctions for the ruin of the southern African country that once exported food, tobacco and minerals. Today, Zimbabweans struggle to survive inflation in excess of 100,000 percent, crippling shortages of food, water, electricity, fuel and medicine. The British charity Save the Children said Friday the number of children who die before their fifth birthday has more than doubled from 59 per 1,000 births in 1989 to 123 per 1,000 in 2004. Western sanctions introduced after independent monitors said 2002 elections were rigged involve visa bans and frozen bank accounts for Mugabe and 100 of his cronies, but he has convinced many supporters that they are to blame for the country's woes. Mugabe's critics say it was the government-ordered, often violent eviction of white farmers to hand land over to blacks that doomed the agriculture-based economy. A third of Zimbabwe's population, an estimated 5 million people, are political and economic refugees. With no provisions for overseas voting, some were participating in a mock online election. In London, the Zimbabwe Vigil group was holding elections in front of the Zimbabwe Embassy for frustrated refugees.