By Helen Murphy and Nelson Bocanegra
BOGOTA (Reuters) - Frustrated by increased rebel attacks and Colombia's surprising friendship with socialist neighbor Venezuela, a former ally of President Juan Manuel Santos has become the first to throw his hat in the ring for the 2014 presidential election.
Oscar Ivan Zuluaga, who was finance minister under Santos' predecessor Alvaro Uribe, says he worries Colombia is going back to the days when it was too dangerous to go out at night as drug-funded FARC rebels erode security gains of the past decade.
"In terms of security there's a backslide," Zuluaga told Reuters in his first interview with foreign media after announcing his intention to run for the presidency this week. "There has been a deterioration and that has reduced confidence."
Santos, who has not said whether he will seek re-election, has seen his approval ratings slide amid allegations of corruption in Congress and a barrage of sniping by Uribe, his former boss and ally, that rebels are gaining the upper hand against government troops.
Zuluaga looks likely to receive backing from Uribe, who served two terms as president and is now seen as the de facto opposition leader. Uribe is barred by law from running again but is Colombia's most influential political power broker.
Uribe and Zuluaga are Santos' most potent critics, slamming him for seeking peace "above all else" with the Revolutionary Armed Forces of Colombia (FARC) guerrilla army, which has fought since the mid-1960s in a war that has killed tens of thousands.
Santos has said he would consider peace talks with the rebels if they ceased attacks on civilian and military targets.
"I'm not saying that only militarily can we achieve peace ... but it's very important to weaken them structurally. We can never give in to them, never show signs of weakness," Zuluaga, 53, said in an interview on Wednesday in a park in the capital Bogota.
"We have to ensure there isn't a premature obsession for a negotiated peace."
Even as Santos faces criticism for a perceived deterioration in security, he is also being credited with some of the heaviest blows against the FARC - both as Uribe's defense minister and since he became president.
He is responsible for killing and capturing several key rebel commanders and severely weakening its fighting force.
Still, in the first four months of the year, FARC attacks increased 66 percent compared with the same period of 2011.
Zuluaga and Uribe also object to Santos' renewed ties with Venezuelan President Hugo Chavez - whom they accuse of harboring FARC fighters - after years of antagonism during Uribe's presidency.
"Santos wants to be friends with the entire world," said Zuluaga, a former senator and provincial mayor.
One of Santos' first acts after taking the presidency in August 2010 was to restore diplomatic ties with Chavez's socialist government, ending a cross-border dispute some had feared could lead to armed conflict.
Zuluaga, whose family manages one of Colombia's largest steelmakers, launched his bid to become presidential candidate just days after his patron Uribe pulled out of the ruling Partido de la U.
Created in 2005 by Santos and Zuluaga to support a constitutional change that allowed Uribe a second term, the Partido de la U is packed with both Santos and Uribe supporters.
An economist who speaks fluent English, Zuluaga would need to convince the bulk of the current party that he would make a better leader than Santos in order to win its backing.
But already scores of Santos backers have shifted to Uribe following a botched congressional reform of the legal system that would have led to the dismissal of cases against politicians accused of ties to right-wing paramilitary groups.
The fiasco helped cut Santos' approval by 16 percentage points in two months to 48 percent, according to a Gallup poll.
URIBE "TRANSFORMED" COLOMBIA
While Zuluaga's chances of beating Santos are seen as slim right now, he plans to travel Colombia over the next two years to drum up support, and he could also have Uribe's full support.
Many wonder whether Uribismo, as his movement is known, could succeed without him as its candidate, but Zuluaga says Uribe's success as president and continued high profile will mean that the "loyalty to his ideas" will stay strong.
"His government, in which I was a key player, transformed the country. We can't forget that, and that remains in the hearts and minds of Colombians," Zuluaga said.
When Uribe took office in 2002, FARC rebels were at the city limits of Bogota and able to launch an attack during his inauguration that killed 21 people. By 2011, the murder rate was halved and kidnappings were down 90 percent.
The dramatic improvement in security helped fuel an economic boom and a surge in foreign investment, enabling oil and mining companies to operate without the constant threat of attacks.
Still, ties to Uribe may also damage Zuluaga's chances.
Accusations of corruption have dogged Uribe's inner circle, and some of his supporters have been jailed for dealings with illegal militia groups and spying on rivals.
As finance minister from 2007 to 2010, Zuluaga steered the economy through a period of record growth and then through a slowdown at the end of 2008 during the global financial crisis.
While he concedes the economy is now easing mainly due to external factors and that investors remain pleased with Colombia, he said the government "needs to react more quickly."
Economic growth is likely to slow to 4.8 percent this year from 5.9 percent in 2011, although foreign investment remains strong.
"It's the biggest treasure Colombia has today, the investment recovery," said Zuluaga. "The investment dynamic was made possible because (Uribe's) security policies generated confidence in everyone, Colombians and foreigners alike."
(Editing by Jack Kimball and Eric Walsh)