Reprinted with permission from Called to Colombia:
John Manuel Santos was the early front-runner to succeed Uribe. Santos is running as a part of the newly formed Partido de la U – literally, the party of Uribe. Santos served as the Defense Minister under Uribe, and is a part of a political and media family that has long been involved in Colombia's politics. Santos, and others in the Partido de la U, are generally running on a platform to continue Uribe's security and economic measures. Santos has been hindered by several of the scandals of Uribe's time in office, particularly those around the issues of human rights abuses by Colombian military forces and cross-border attacks.
Antanas Mockus, running as the Green Party candidate (also a newly formed party), has been the surprise of the election season. A former mayor of Bogota, Mockus has run a very spirited campaign that has seen a huge rise in popularity and support from young people and online activists. Mockus is running a campaign based on increasing citizenship as a way to develop the country – a theme that he used with generally good results in the city of Bogota. Mockus also interestingly has teamed up with previous rival Sergio Fajardo, a popular former mayor of Medellin, and two other former mayors of Bogota, to run as a unified group that is seeking to bring the significant changes of Colombia's two leading cities to the entire country. Mockus has been a colorful character in Colombian politics (not too often that you get to talk about elephant rides, mooning, and superhero stunts in politics, right) but has become a more traditional candidate as his poll numbers have risen.
The Conservative Party is represented by Noemi Sanin, who has a long history in Colombian politics. The Liberal Party is represented by Rafael Pardo. Polo Democratica is a left party, and is represented by Gustavo Petro. The last major candidate is German Vargas Lleras of the Cambio Radical (Radical Change) party, a close Uribe ally.
A good site for English language news concerning the election is Colombia Reports 2010 Election site.