Polls give Uribe a commanding lead over his challengers
Washington's closest ally in Latin America, Colombia, looks set to buck the trend of left-wing victories in the region.
Four years ago President Alvaro Uribe won office promising to deliver greater security.
His 30% lead in the opinion polls suggests most Colombians believe he has kept his word.
After four decades of conflict between left-wing Farc guerrillas and right-wing paramilitaries, the Colombian state is too weak to control large parts of the country.
But after boosting military spending President Uribe claims to have reclaimed the country's urban centres.
"President Uribe is the most popular president in Colombia's history," says Alfonso Cuella, who edits the weekly news magazine Semana.
"Colombia has around 1,100 towns and cities. Four years ago between 300 and 400 of them did not have police. Now they all do."
Take the town of Viota, two hours drive from Bogata. Before President Uribe came to power, it was controlled by Farc. Now it has an army base, a police station and thriving market.
Hector Cante, who is now the elected mayor of Viota, fled the town the day after his father was killed by Farc guerrillas eight years ago.
Now he has returned and says life is back to normal.
"Viota wasn't going anywhere when Farc was here. It was a dead town," he said.
"Now there are businesses and commerce and we are growing coffee."
Both the guerrillas and the paramilitaries draw their strength from Colombia's coca harvest that produces 90% of the world's cocaine supply.
Uribe has offered paramilitaries immunity for demobilisation
The US spends $600m a year on the war against drugs in Colombia, destroying coca fields by aerial spraying. The drug cartels have responded by planting more crops.
Earlier this year a US government survey reported that the amount of land under coca cultivation had increased by 26%.
US officials said that was because of more thorough surveying techniques but many Colombians have concluded that as long as there is a demand for cocaine, the illegal trade will continue.
"For Colombia it's just the same thing to sell 300 tonnes at $20,000 per kg as it is to sell half that amount at twice the price," says Jorge Orlando Melo, a columnist on Colombia's main newspaper El Tiempo.
President Uribe's main opponent in the election is a law professor, Carlos Gaviria.
During the campaign he has tripled his support, with opinion polls now showing him on 25% against 55% for the president.
For a first round victory the president needs more than 50% of the votes in Sunday's election.
Prof Gaviria's supporters say they are hopeful he can force a second round.
Prof Gaviria, who once taught President Uribe at university, advocates social reforms to narrow the gap between rich and poor.
His campaign has also highlighted the issue of human rights.
The US state department and human rights organisations have reported killings and acts of torture carried out by the paramilitaries against suspected Farc members.
The president stands accused of being too close to the paramilitaries.
One of his most controversial decisions has been to offer most of them immunity in return for their demobilisation.
The government claims the paramilitaries are genuinely disbanding.
But many Colombians have their doubts. They believe the paramilitaries are taking the offer of immunity but maintaining their interest in growing drugs, often on stolen land.
The land issue is particularly acute for Colombians who have been forced to flee their homes.
Around 5% of the population have been internally displaced and many of them live in wretched conditions on the outskirts of the big cities.
Ciudad Bolivar, just outside of Bogata, is home for more than one million of Colombia's dispossessed.
They say the paramilitaries still control the area, making money mainly out of protection rackets.
Human rights organisations report that the paramilitaries have been responsible for the disappearance of 170 union leaders and other activists in Ciudad Bolivar alone since the start of 2005. They believe most have been murdered.
For the past five years, Denise Rengel has lived in a one-room wooden shack in Ciudad Bolivar with her six children.
When it rains heavily she has to move elsewhere for fear that the ramshackle structure might collapse.
"I think the government is giving more help to the fighters than to the displaced people," she says. "They treat them like kings, but leave us poor."