The mudslinging has distracted attention from talks with the country's main rebel group to end the country's half-century internal conflict, which had been expected to be a key issue going into Sunday's election.
Much of the blame for the dirty campaigning falls on two former allies whose public feuding has divided Colombia the past four years: President Juan Manuel Santos and his still-powerful predecessor, Alvaro Uribe.
Despite presiding over what may be South America's best-performing economy, Santos is struggling amid relentless attacks by Uribe and his hand-picked heir, former finance chief Oscar Ivan Zuluaga. Polls say the two are running neck and neck, well ahead of three other candidates but with neither likely to garner the 50 per cent needed to avoid a runoff.
But those policy differences have taken a backseat to endless bickering and near-daily bombshells that have Colombians shaking their heads in disgust.
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It began with media reports that Santos' campaign manager, JJ Rendon, received USD 12 million from the nation's biggest drug traffickers to negotiate their surrender. The information was based on three-year-old, leaked testimony to Colombian prosecutors from a drug cartel boss jailed in the US.
Two days later, authorities arrested a computer expert who worked for Zuluaga's campaign, accusing him of hacking into the emails of FARC negotiators and even Santos. Zuluaga denounced the arrest as a ploy to derail his candidacy.
Uribe, without presenting any evidence, then accused Rendon of funneling USD 2 million from the alleged drug-dealer payments to Santos' 2010 campaign.