By Helen Murphy and Luis Jaime Acosta
BOGOTA (Reuters) - A former Colombian guerrilla insurgent who is trying to become the country's first leftist president, Gustavo Petro said he would focus on narrowing its yawning gap between rich and poor if elected.
The 57-year-old leftist economist, who was mayor of Bogota from 2011 to 2013, ranks second in polls to replace President Juan Manuel Santos and is pledging to change the nation's economic model, by taxing owners of unproductive land and shifting away from oil and coal.
"I want to transform the country. It's what I have wanted since I was a boy," Petro said in an interview late on Tuesday. "The core generator of problems in Colombia is inequality."
The election may determine the fate of Colombia's fragile peace process, which ended five-decades of war with Marxist FARC rebels but angered many by giving their commanders a political voice instead of a jail cell, and highlighted the wealth divide Petro is targeting.
Petro's proposals, which include expanding education, clean energy and a tax overhaul, have spooked some investors who fear he will expropriate land and turn Colombia into another Venezuela, a charge he denied.
"We would not be an ally of Venezuela, because Venezuela entered the world of the fossil economy," he said, referring to Colombia's crisis-hit socialist neighbour. Petro added that he would gradually eliminate oil, coal and gas and replace it with energy from clean sources like wind and water.
Petro will hike taxes on unproductive fertile land, encouraging landowners to sell to the state to pass on to poor farmers. That may upset cattle ranchers, among others.
"A tax cannot be called expropriation; it's a tax on productive land," he said.
Once a member of the now-defunct M19 rebel group, Petro's election as Bogota mayor was seen as proof that politics was the way forward for insurgent movements like the FARC, which demobilized last year and formed a political party.
But in late 2013 he was removed from his post - the most powerful after the presidency - by the inspector general for mismanagement of garbage collection and banned from holding office for 15 years, a ruling that brought thousands to the streets and was later overturned.
Ivan Duque, a protege of right-wing former President Alvaro Uribe, is leading Petro in polls by about 10 points in Colombia, a country of 50 million that has historically been governed by the right.
A father of six, Petro rails against the Colombian traditional political class, accusing it of corruption and enriching itself at the expense of the poor.
Petro's Colombia Humana party won just six seats out of 280 in the recent legislative election, making it tough for him to push radical reforms through congress. He said he would seek alliances with centre, left and other minority parties or call for a change to the constitution through a constituent assembly.
He plans to sell bonds to finance the land purchases and move poor farmers - like those who grow coca, the raw material for cocaine - to grow legal crops.
To contain the fiscal deficit, he would promote another tax reform to raise duties on corporate dividends and foreign profits and eliminate tax exemptions for large investors.
"An investor is a gambler and the first thing he does is to examine the rules of the game. We want to put the rules of the game on the table, without hidden cards, we want to move from an extractive economy to a productive economy," he said.
A first-round ballot will be held on May 27, but if none of the candidates get more than half the votes, a second round will be held in June.
(Reporting by Helen Murphy; Editing by Christian Plumb and Richard Chang)