Colombia is holding presidential elections on 30 May 2010. There are six main candidates contesting the first round.
If none of them gets an absolute majority, the top two candidates will go into a second round on 20 June.
Incumbent President Alvaro Uribe is banned from running again under the country's constitution, which does not allow for more than two terms in office.
Citizens 18 years and older who are not serving a sentence are eligible to vote. Here we profile the main candidates:
JUAN MANUEL SANTOS, Social National Unity Party
Juan Manuel Santos, 58, is running for the Social National Unity Party, also known as Party of the U.
He comes from an influential Colombian family. His great-uncle, Eduardo Santos, was president from 1938 to 1942 and owned the country's largest newspaper, El Tiempo. His cousin, Francisco Santos, is the current vice-president.
He served as defence minister under President Alvaro Uribe from 2006 until 2009. As such, he was instrumental in carrying out the president's "democratic security policy", aimed at increasing the presence of the security forces throughout the country and driving back Colombia's main left-wing rebel group, the Farc.
Many Colombians credit him with an increase in security, but others argue the victories he achieved came at too high a price.
He oversaw Operation Checkmate, the successful rescue by the military of 15 high-profile hostages, including the former presidential candidate Ingrid Betancourt.
He was also in charge when the Colombian military mounted a controversial air raid into Ecuador during which senior Farc leader Raul Reyes and 25 other people were killed.
The Colombian military says the killing of Mr Reyes was a major blow to the Farc but Ecuador continues to be incensed its airspace was violated.
An Ecuadorean court has issued an arrest warrant for what the judge called Mr Santos' intellectual role in the attack.
During Mr Santos' tenure as defence minister, the military was also rocked by a scandal called "false positives". A number of senior officers were accused of the extrajudicial killing of civilians, leading to the resignation of the head of the army.
Mr Santos says that if elected, he will continue to implement the policies of President Uribe, with a strong emphasis on combating the drugs trade and the Farc.
He has also promised to invest in Colombia's infrastructure to create more jobs. He says his government would aim to have at least one person in every family working in a formal job and has urged Colombians to move away from the informal economy.
ANTANAS MOCKUS, Green Party
Antanas Mockus, 58, is the presidential candidate for the Green Party.
He is a mathematician whose parents emigrated to Colombia from Lithuania. Twice-mayor of Bogota and former rector of the National University, he is known for his commitment to education and his grass-roots approach to politics.
He is sometimes ridiculed for the stunts he uses to grab people's attention. He once mooned his students when they became too raucous and dressed up in a spandex suit as "Supercitizen" in an effort to convince Bogota residents to abide by traffic rules.
Asked on national radio what his biggest vice was, he replied "Coveting the wives of others". His answer shocked some conservative listeners, but was characteristic of what his supporters say is his direct and honest approach to politics.
He also disclosed that he had been diagnosed with Parkinson's Disease, but stressed that it would not impair his ability to lead the country.
His focus on education appeals to many young voters who have played a big role in promoting his campaign through social networks like Twitter and Facebook. But some older voters say he lacks the toughness necessary to confront the criminal gangs which in many areas have taken over the drugs trade from dismantled paramilitary groups.
Mr Mockus says Colombians need to be convinced that drug-trafficking does more harm than good. He argues that a cultural change is needed before the war on drugs can be won.
Some analysts question whether his policies, which have worked well in urban areas, would draw as many supporters in rural parts of Colombia, where his party lacks the political networks other more established groups have.
NOEMI SANIN, Conservative Party
Noemi Sanin, 60, is the candidate for the Conservative Party and has stood for president twice before. She served as a communications minister and foreign minister in previous governments.
She has also been Colombian ambassador to London, Madrid and Caracas.
Ms Sanin says Colombia needs a government that fights for its security and against poverty. She argues that she has the best credentials out of all the candidates to lead that fight.
She backs the current government's "democratic security policy" and has vowed to maintain it. But she has criticised Mr Uribe for not doing enough to create more employment and educational opportunities.
Ms Sanin thinks Colombia's lack of infrastructure is a major factor in its underdevelopment and lack of security and promises to raise private capital to improve it.
She says the Conservatives will uphold the constitution and the rule of law.
She argues that many families rely on growing coca crops to survive and thinks a better agrarian policy is needed to allow farmers to prosper.
GUSTAVO PETRO, Polo Democratico
The fifty-year old economist Gustavo Petro is running for Polo Democratico.
The descendant of Italian immigrants was part of the M-19 guerrilla movement. After the group was demobilised, he won a seat first in the House of Representatives and later in the Senate.
He has told voters that his humble background, his tough life and his commitment to social justice set him aside from the other candidates and guarantee he will implement real change.
Even though he is a vehement opponent of President Uribe, he has vowed to continue his "democratic security policy". However, he argues that any armed approach would have to be combined with a drive towards social equality to achieve a change in the Farc mentality.
Despite his past as a guerrilla member, he has been scathing in his criticism of the Farc, whom he accuses of human rights abuses. He has compared them to Cambodia's Pol Pot, saying that they are "not revolutionaries, they are not left-wing, they're right-wing and they are criminals."
He says that the Colombian political culture needs to change radically to eradicate corruption and scandals such as that of the "parapoliticos", a group of legislators who were jailed for their connections to paramilitary groups.
His priority is for land reform and agrarian development.
He advocates a model of justice which would allow drug dealers and growers to turn themselves in and make reparation to their victims in exchange for more lenient sentences.
He opposes the aerial spraying of drug crops which he argues just moves the trade on rather than eradicating it.
He was voted worst-dressed candidate by national radio station RCN.
GERMAN VARGAS LLERAS, Radical Change Party
German Vargas Lleras, 48, is running for the Radical Change party. He comes from an influential political dynasty. His grandfather, Carlos Lleras Restrepo, was president of Colombia from 1966 to 1970. His uncle has also been a candidate for the presidency. He has served various terms in the Colombian Senate.
He wants to strengthen Alvaro Uribe's military attack on the Farc. He is highly critical of Venezuelan President Hugo Chavez and advocates the establishment of a border control to close down the many loopholes he says the Farc use to criss-cross between the two countries.
He also backs many of the current government's policies to combat drug trafficking. He favours the extradition of major suspects to the US for trial, thinks the government should continue to seize de assets of those convicted on drugs charges and supports crop-spraying programmes.
Mr Vargas Lleras is opposed to a dialogue with the Farc. He says the group has committed crimes against humanity and cannot be pardoned.
He lost several fingers of his left hand when he was sent a bomb hidden in a book.
RAFAEL PARDO, Liberal Party
The 57-year old economist is the Liberal Party's candidate for the presidency. It is the second time he is running for the presidency. He has served as defence minister under President Cesar Gaviria (1991-1994).
He says that as president he would provide the conditions for economic competition, promote equality, provide security, and uphold a state that provides its citizens freedom.
He is an academic who has written six books, mainly dealing with the conflict between he state and the guerrillas of the Farc and the paramilitaries.
He believes that the state needs to be in control of the territory in order to end the war with the guerrillas. He has not ruled out a dialogue with the Farc but says that reparations would have to be made to the victims of the conflict.
He thinks greater development in rural areas is key to ending the conflict. Only if young people are given employment will they stop joining guerrilla groups, he says.
He argues that the same applies to coca growing. Unless illegal crop eradication programmes are combined with incentives to stop growing them in the first place, they will not work, he argues.