By Helen Murphy
BOGOTA (Reuters) - Colombian Vice President German Vargas Lleras resigned on Wednesday, a move widely expected to herald his push for the presidency next year even as he says he is undecided.
President Juan Manuel Santos has nominated former national police chief General Oscar Naranjo as Vargas' successor, stating he wants Naranjo to strengthen security and the drive to stamp out coca cultivation.
In his resignation letter to the Senate, Vargas, 55, said he had not yet decided whether to run for president, but would leave office to make sure he was eligible to compete in 2018.
He will step down on Tuesday, according to his letter.
A growing number of media commentators and political analysts believe Vargas, a member of the center-right Cambio Radical party, will run against the candidate of Santos' ruling U party.
As vice president since 2014, Vargas focused on infrastructure projects, spearheading improvements to roadways and building subsidized housing for the poor.
He has not publicly criticized Santos' 2016 peace agreement with the leftist Revolutionary Armed Forces of Colombia (FARC). But local news media have reported he is against the deal's terms allowing rebels to enter politics and receive no jail time.
Like Santos, Vargas comes from one of the most powerful families in Colombia. He is the grandson of former President Carlos Lleras Restrepo and nephew of former presidential candidate Carlos Lleras de la Fuente.
He was unharmed in a 2005 car bomb in Bogota, which authorities blamed on the FARC. But in 2002 Vargas lost fingers on his left hand when he opened a letter bomb at his congressional office.
In 2015 Vargas had surgery to remove a benign brain tumor.
Santos' nomination of Naranjo as vice president needs to be approved by Congress.
Naranjo, 60, was part of the government negotiating team in Havana that worked for four years to clinch a peace agreement with the FARC. The accord ended the 52-year war with the guerrillas, who are beginning to hand in their weapons.
He served as head of the national police force between 2007 and 2012.
(Reporting by Helen Murphy; Additional reporting by Luis Jaime Acosta; Editing by W Simon and Leslie Adler)