For decades, Colombians voted with an eye on the bloody conflict with leftist rebels that dominated their country and politics.

But on Sunday they were casting their ballots in the first presidential election since the signing of a peace accord with the nation's biggest rebel group FARC to end the conflict and were weighing issues like corruption, inequality, crime and relations with their crisis-plagued neighbor Venezuela.

Early results Sunday showed conservative Ivan Duque leading with 41 percent of the vote, indicating a runoff is likely.

The two leading candidates have presented dramatically different visions for both Colombia's economic model and the future of its divisive peace process in a polarizing campaign driven by a wave of anti-establishment sentiment.

Leading the polls is conservative former senator Duque, the protege of former President Alvaro Uribe, the leading critic of the peace deal, but surveys suggest he is unlikely to get the more than 50 percent of votes required to avoid a June runoff. He's being chased by Gustavo Petro, a former guerrilla and ex-Bogota mayor, whose rise has triggered business concerns he would push Colombia toward the left and rattle markets.

At least two other candidates trail within reach of obtaining the second spot and a place in any runoff.

"If he (Duque) wins, he has an opportunity to bridge some of these divides in Colombia," said Michael Shifter, president of the Inter-American Dialogue.. "But the big unknown is what Uribe's role will be."

The campaign has sparked fears on both the left and right of Colombia's political spectrum, with Duque's critics cautioning that his presidency would be tantamount to a constitutionally barred third term for Uribe. Though hugely popular among Colombians for improving security and weakening illegal armed groups, Uribe also presided over grave human rights violations by the military.

Meanwhile, Petro and his populist platform have drawn comparisons from critics to the late Venezuelan socialist leader Hugo Chavez, who Petro once admired. He brought Chavez to Colombia in 1994 shortly after the Venezuelan paratrooper was released from jail, where he was sent for staging a military coup, and the relationship between the two has dogged Petro throughout his campaign.

Petro says Venezuela's economic model doesn't work and calls himself a "strong adversary" of the neighboring country's current president, Nicolas Maduro.

He is proposing overhauling Colombia's economic model to free it from dependence on oil exports and instead boost agricultural production through land reform. His campaign says he'd dramatically increase taxes on unproductive lands to encourage landholders to sell them to the state.

Hollman Morris, a Colombian journalist who has been supporting Petro's campaign, said Petro's trajectory from leftist militant to congressman and mayor and now possibly to the presidency is an important sign of Colombia's political evolution as voters show they are willing to move beyond long-held fears of leftist contenders.

"We think Colombia has reached an important level of maturation," Morris said at Petro's campaign headquarters. "But also, Colombia has begun to realize the decline of its traditional political class, which is totally involved in corruption."

In the final days before the vote, Petro accused officials of failing to address a voting software glitch that he said could lead to fraud.

That led to an outcry among his competitors and a rare intrusion in the campaign from outgoing President Juan Manuel Santos, who said "leftist extremists are the same as right-wing extremists: They invent frauds where they don't exist."

Aside from the economy, Petro and Duque differ on the peace accord, which has been slow to be implemented and remains controversial among many Colombians who believe it granted overly generous terms to demobilized guerrillas. Petro supports the accord while Duque has said it needs "correcting."

With Colombia's political polls notoriously unreliable, there's still room for an upset with candidates like former Medellin Mayor Sergio Fajardo and former Vice President German Vargas Lleras trailing close behind.

Fajardo, who is credited with Medellin's transformation from a hotbed of crime into a growing tourist destination, has run on a platform of rooting out corruption and boosting social programs. Vargas Lleras is pledging to create more than 1 million new jobs.