Colombian President Juan Manuel Santos concluded a reshuffle of his cabinet, changing six of its 16 ministers as he battles slumping approval ratings. In one major change halfway through the president\'s four-year mandate, Santos appointed lawyer Fernando Carrillo as his new interior minister, replacing Federico Renjifo, who was named mines and energy minister. Renjifo\'s post is critical in Colombia, which has becomes Latin America\'s fourth-largest oil producer. He replaces Mauricio Cardenas, who has been tapped to lead the Finance Ministry. Santos also appointed Cecilia Alvarez-Correa as the new transport minister, while economist Alejandro Gaviria took up health and Juan Gabriel Uribe got the environment. Of the 16 ministries, five were entrusted to women, including the Foreign Ministry, where Maria Angela Holguin stayed on as the country\'s chief diplomat. Santos also denied the resignation of Defense Minister Juan Carlos Pinzon, who will continue to serve in the administration. In setting his new cabinet, Santos created a post with ministerial rank to engage in \"exploratory discussions\" with leftist FARC rebels to lay the groundwork for a full-fledged peace process. He has appointed former Bogota mayor Luis Eduardo Garzon as his pointman for the talks. Santos, who took office in August 2010, had a 70 percent approval rating a year ago, but that figure has plummeted to 45 percent.