Presidential elections were held in Colombia on 27 May 2018. As no candidate received a majority of the vote, the second round of voting was held on 17 June. Incumbent president Juan Manuel Santos was ineligible to seek a third term. Iván Duque, a senator, defeated Gustavo Petro, former mayor of Bogotá, in the second round. Duque's victory made him one of the youngest individuals elected to the presidency, aged 42. His running mate, Marta Lucía Ramírez, was the first woman elected to the vice presidency in Colombian history.
The election was held following a peace agreement between the government and the Revolutionary Armed Forces of Colombia (FARC) in 2016, ending over 50 years of conflict. The elections were the first to occur since congress passed legislation in 2015 modifying the presidential term limits, restricting presidents to one four-year term with a formal ban on re-election. The bill also granted the runner-up candidate in a presidential election a seat in the senate, whilst their running mate would become a member of the chamber of representatives. 
Duque, a lawyer and protege of former president Álvaro Uribe, was the nominee for the Democratic Center party. Duque, who was mostly unknown to the public before the election, had a platform encompassing support for innovation, economic recovery and staunch opposition to the peace agreement. 
Petro, a former AD/M-19 member and nominee for the Humane Colombia party, ran a progressive populist campaign that focused on reducing inequality and implementing universal healthcare and environmental protection. Petro narrowly surpassed centrist candidate Sergio Fajardo in the first round by just over 1%, permitting him to qualify for the run-off. 
Duque was victorious in the second round, earning 54% of the vote to Petro's 41%. Duque won 24 of Colombia's 32 departments, performed well in the inland regions and received over 77% of the vote in the Andean department of Norte de Santander. Duque assumed office on 7 August. Meanwhile, Petro became a senator, and later the future president of Colombia, whilst his running mate, Ángela Robledo, became a member of the chamber of representatives.
Background.
During the previous election held in 2014, a second round was held as no candidate attained more than 50% of the vote. The candidates were incumbent president Juan Manuel Santos of the Party of the U and Óscar Iván Zuluaga of the Democratic Center. The election centred on the issue of how to continue peace negotiations with the Revolutionary Armed Forces of Colombia (FARC). In the run-off, Santos defeated Zuluaga, earning 50% of the vote to his opponent's 44%.
In June 2015, both houses of congress approved legislation limiting presidents to a single four-year term with a formal ban on re-election, restoring the term limits that were in place before 2005. President Santos, who submitted the bill upon re-election in the 2014 presidential election, said the re-election ban would restore a balance of power in Colombia. The bill faced criticism from supporters and members of the Democratic Center party led by former president and rival of Santos, Álvaro Uribe. They argued the purpose of the bill's introduction was to prevent Uribe from seeking a non-consecutive third term to the presidency. Edward Rodríguez, a Democratic Center member of congress, described the re-election ban as "revenge against Uribe".
On 27 September 2016, the government signed a peace agreement with the FARC. A referendum took place on 12 October to ratify the deal; however, voters narrowly rejected it. President Santos then negotiated with staunch opponents of the agreement like Uribe and reentered into talks with the FARC. The FARC and the Colombian government agreed to a revised peace deal on 24 November. The modified agreement included changes, such as an agreement that the deal would not be part of the constitution. Rather than put the revised deal through another referendum for ratification, Santos sent the agreement to congress. The Senate voted to ratify the deal on 29 November, which was followed by the approval by the chamber of representatives. The ratification marked an end to 50 years of conflict.
Electoral system.
Colombian Presidents are elected for four-year terms using a two-round system; if no candidate receives a majority of the vote in the first round, a runoff is held between the top two candidates. The Vice President is elected on the same ticket as the President. Presidents are limited to a single four-year term and Article 191 of the constitution requires candidates to be Colombian by birth and at least thirty years old. 
In line with the constitution, Colombian citizens by birth or by naturalization, aged eighteen or older have the right to vote. Several scenarios can cause the loss of the right to vote, as outlined in the constitution. Citizens in detention centers can vote from the establishments determined by the National Civil Registry. The civil registry inscription is not automatic, and citizens must go to the regional office of the Registry to register.
Legislative act # 2 of 2015 established that the runner-up in the presidential elections is given a seat in the Senate and their Vice President candidate will become a member of the House of Representatives. ;ref name="ActoLegislativo02/2015" ; ;/ref ;
Candidates.
The following lists display candidates in the order they appeared on the ballot and show the most recent political office they have held as of the time of the election.
Candidates that withdrew.
The Common Alternative Revolutionary Force withdrew its presidential aspiration on 9 March 2018, stating the health problems of its candidate Rodrigo Londoño, as the reason.
Juan Carlos Pinzón, who had previously served as defence minister and ambassador to the United States under president Juan Manuel Santos, launched his candidacy for Casa de Nariño in 2017. Pinzón withdrew from the race on 16 March 2018 to become Vargas Lleras' running mate.
Piedad Córdoba and her vice presidential candidate terminated their candidacy on 9 April 2018.
Viviane Morales and her vice presidential candidate Jorge Leyva Durán, of the "Somos Región Colombia" party, retired their candidacy on 2 May 2018. After, Morales adhered to Iván Duque's campaign, while Leyva joined Germán Vargas Lleras' candidacy.
Primaries.
Two coalitions, the right-wing Great Alliance for Colombia and left-wing Social Inclusion for Peace, held primary elections concurrently with the legislative elections on 11 March.
Great Alliance for Colombia.
Three candidates sought the nomination of the conservative Great Alliance for Colombia:
Results.
Duque won the nomination, and following his victory, he selected the runner-up, Ramírez, to be the alliance's vice presidential nominee.
Social Inclusion for Peace.
The progressive Social Inclusion for Peace alliance was composed of Humane Colombia, the Indigenous and Social Alternative Movement, Patriotic Union and the List of Decency coalition. Two candidates sought the alliance's nomination:
Results.
Petro secured the nomination by a large margin and won all departments, losing only in Caceido's home department of Magdalena. Following the primary election, Petro selected Ángela Robledo of the Green Alliance and a member of the chamber of representatives as his running mate.
Campaign.
According to polling data, significant issues amongst voters were unemployment, healthcare, corruption and the FARC peace agreement.
Iván Duque, a lawyer, senator, protege of Uribe, and the nominee for the Democratic Center party, campaigned on promoting innovation, job creation, economic recovery, environmental preservation and opposing the FARC peace agreement. Before his nomination, most of the public was not familiar with Duque. He rose to prominence during the 2016 peace referendum due to his staunch opposition. However, he stated that Duque was still in favour of peace but aimed to keep the FARC out of Colombian politics and prosecute FARC and National Liberation Army (ELN) rebels. On narcotics, Duque expressed his support for the war on drugs and sought to eliminate all coca production. He emphasised a message of opposing corruption and implementing economic reform; for instance; he proposed a simplification of the tax code. Due to Duque's youth and light experience, opponents and critics painted him as unprepared to head the executive branch, leading some to claim further that the senator was a puppet of Uribe. Duque countered these claims by saying it was time for a new generation to take over, and whilst he did highlight his close ties to Uribe, he emphasised that he was "his own man". Critics also attacked Duque for his opposition to the peace agreement, his refusal to rule out fracking and alleged ties to paramilitary groups.
Economist Gustavo Petro of Humane Colombia, a former mayor of Bogotá and former M-19 guerilla who was previously a candidate in the 2010 presidential election, ran a populist campaign focusing on decreasing inequality and tackling climate change. Supported by a coalition of left and centre-left parties, Petro also emphasised workers' rights and campaigned to improve labour conditions in both urban and rural areas. He aimed to reduce poverty by implementing land reforms and establishing a "popular bank" that would offer loans to impoverished citizens. Petro supported the introduction of state-funded universal healthcare that would replace the unpopular private-funded system. Furthermore, he sought to restrict the use of fossil fuels and intended to ban any further exploration of mining and fracking in favour of renewable energy sources. Several months before the election, Petro survived an assassination attempt when a bullet pierced through his armoured van. He presented himself as a successor to prominent slain left-wing politicians such as Jorge Eliecer Gaitan and Luis Carlos Galán. Petro furthermore highlighted the need to end political persecution in the country. Petro's opponents claimed that he would "turn Colombia into another Venezuela", citing his prior support for former Venezuelan president Hugo Chávez. Critics said his policy proposals would not attract foreign investment and that his plans to abandon non-renewable energy, which accounted for 2-4% of Colombia's GDP, were not feasible at the time. Opponents also claimed that his policies would result in an economic disaster.
Veteran politician Humberto De la Calle, who served as vice president to Ernesto Samper, was the nominee for the Colombian Liberal Party. De la Calle played a crucial role in negotiating the peace deal with the FARC and campaigned on policies to assist the country post-conflict, including investments in job creation and regions that were heavily affected by the conflict. He entered the presidential race to keep Duque from winning the presidency. De la Calle supported increasing environmental protection and stricter criteria for the issue of mining licenses, both as a means of promoting ecotourism. Due to the high presence of labour inequality and gender-based violence, De la Calle announced his intention to establish a ministry of women to tackle these issues. He furthermore proposed a significant reform of the education sector, seeking to transform the financing and structure and change the ministry of education to the ministry of intelligence. De la Calle's proposals included other policies with broad support amongst the youth, such as modifying the unpopular student loan program and abolishing compulsory military service. Whilst on the campaign trail, De la Calle struggled to gain momentum and often trailed his opponents in the polls. The peace agreement, a controversial topic amongst voters, did not help boost support for De la Calle. His 30 years of political experience proved a double-edged sword; some voters saw this as a benefit, but others concluded that De la Calle was a part of the elite. The Liberal party's severe dis-unity and rupturing also hurt him. But De la Calle's campaign suffered a severe downturn when Liberal party leader and former president César Gaviria announced before the first round that the Liberal party would support Duque in the run-off, implying that the party had lost confidence in De la Calle's candidacy.
Sergio Fajardo, a mathematician, former mayor of Medellín, former governor of Antioquia and previously a vice presidential candidate in the 2010 presidential election, won the nomination of the Colombia Coalition, an alliance composed of the Alternative Democratic Pole, the Green Alliance and his Civic Compromise party. Fajardo's platform encompassed education and the environment. He intended to increase the education budget by 10% and boost enrollment nationwide to combat poverty. Fajardo supported the peace agreement, although he presented himself as a moderate centrist alternative to Duque and Petro. On the campaign trail, Fajardo expressed concern about vote buying and advocated for a transparent electoral and judicial process. Whilst he campaigned on being the fiscally reliable candidate, he faced criticism from opponents who highlighted a dramatic debt increase that occurred during his tenure as governor of Antioquia. Fajardo considered polarisation a threat to Colombian politics and sought to present himself as