By Jack Kimball
BOGOTA (Reuters) - Colombian President Juan Manuel Santos said on Friday he will take his time replacing other members of his Cabinet after accepting the resignation of the finance minister this week, in a move aimed at bumping up his slumping popularity.
At the midpoint of his four-year term, the 61-year-old former defense minister has been battered by criticism in recent months over a rise in attacks by Marxist guerrillas and a justice reform fiasco that has weakened his hand in Congress.
The overhaul of his Cabinet two years into his presidency is aimed at strengthening his support base within the ruling national coalition ahead of his likely re-election run in 2014, and muting criticism of some of his ministers' job performance, experts say.
"Remember we're in a National Unity Government so all the parties want to feel represented in the Cabinet," Santos said in a statement on the presidency's website. "It's not easy to combine all these factors."
Santos asked all 16 ministers to submit resignation letters on Wednesday to give him a free hand in the shuffle. Finance Minister Juan Carlos Echeverry was the first to go, replaced by current Energy Minister Mauricio Cardenas.
The shuffle may claim the education, health, interior, agriculture and defense portfolios, government sources say.
On Friday Santos accepted the resignation of the transport minister.
Santos must still name a new minister of mines and energy, who would be the third person to hold the post in two years.
Interior Minister Federico Renjifo, a former vice mining minister, was a favorite to replace Cardenas at the helm of the oil and mining sectors, the sources said.
"The Santos administration will continue to provide investor-friendly terms to promote investment in oil and mining, but the sector will confront a messy landscape as the ministry changes hands yet again," Heather Berkman, Latin America analyst with Eurasia Group, said in a note to investors.
Once an investment outcast as drug-trafficking insurgents kidnapped, killed and attacked at will in rural areas, Colombia has seen a dramatic turnaround, attracting record foreign investment over the last decade after a U.S.-backed crackdown.
After winning the presidency in a landslide in 2010 and riding on high approval ratings that let him push key economic and political reforms through Congress, Santos appears to be at the end of his honeymoon period.
Ex-President Alvaro Uribe, once an ally, has started a movement aimed at unseating him. And a growing number of attacks by leftist rebels, especially against oil installations, is a worrying trend for one of the economy's fastest-growing sectors.
A botched attempt to reform the justice sector has thrown Santos' reform agenda into disarray, delaying changes to the pension and tax systems that are seen as key if Colombia wants to move up the investment grade ladder.
Some analysts believe the Cabinet changes could be a move to assemble a team that can start negotiation with Marxist rebels who have battled successive governments for nearly five decades.
"Santos wants a Cabinet that targets two objectives: negotiations with the rebels and the path to re-election," the El Espectador newspaper said in an opinion piece.
Some of Santos's most radical reforms -- such as giving stolen land back to displaced peasants and creating a legal framework for peace -- are seen as setting the groundwork for eventual talks with leftist guerrillas groups.
Nearly every government since the rebels took up arms in the 1960s has tried to reach a negotiated settlement with the Revolutionary Armed Forces of Colombia, or FARC, rebels. But each attempt has failed to end the war.
Uribe has stirred controversy over the last week after he announced via Twitter that Santos had opened negotiations with the FARC in Cuba, a move the government denied.
Such talks would likely fracture Santos' ruling coalition in Congress as well as his own Partido de la U, as some lawmakers would jump ship to oppose negotiating with rebels and take sides with Uribe.
(Additional reporting by Katherine McKeon; Editing by Helen Murphy and Xavier Briand)