BOGOTA -- Is Latin America’s oldest guerrilla group ready to trade bullets for ballots? That’s the issue negotiators began tackling in Havana on Tuesday as Colombia resumed negotiations to end a half-century old civil war that has claimed tens of thousands of lives.

At the center of this round of negotiations is the legal framework that will allow the jungle-hardened Revolutionary Armed Forces of Colombia guerrillas to become a political force. That transformation is fraught with problems. The FARC’s previous attempt to enter politics by creating the Union Patriotica party in 1985 led to bloody reprisals. More than 3,000 UP members and two of its presidential candidates were murdered.

During his opening statement Tuesday, the government’s chief negotiator, Humberto de la Calle, tried to reassure his counterparts.

“We are going to be discussing effective guarantees for the opposition, in particular, for the new movements that will arise out of this process,” he said. “Under no circumstance can we allow a repetition of what happened to the Union Patriotica.”

The meeting comes amid renewed optimism after negotiators announced late last month that they had reached an agreement on the first, and perhaps most contentious, point of the six-part peace plan: land reform and rural development.

Land-related disputes and violence date back at least 80 years, and many believed trying to resolve the thorny issue would sink the talks, said Fernando Hernández, the executive director of Corporación Nuevo Arco Iris think-tank.

“The rural issue is at the very heart of the conflict,” he said. “If you compare the dynamic and public opinion over the last 15 days — before and after [the land] agreement — there’s been a change. There’s a lot more support for the process now.”

But the issue of political inclusion is also a polarizing one, Hernández said.

“There are those who know that a guerrilla force like the FARC is not going to demobilize unless it, and its high command, can fully participate in politics,” he said. “And there are those that believe the state shouldn’t even be at the negotiating table.”

It’s unclear what kind of penalties FARC commanders will face under a transitional justice regime, and whether or not they will be allowed to participate in politics. But critics of the peace process, including influential former President Alvaro Uribe — have raised the specter of rebel commanders sauntering through the Senate and the Presidential Palace.

“The countryside is in ruins and the president and the minister are focused on making agreements with terrorism,” Uribe wrote on Twitter on the eve of this round of talks. The United States and Colombia consider the FARC, which is thought to have about 9,000 active members, terrorists.

On Tuesday, de la Calle said it was too soon to speculate about individual political players.

This will be a “discussion about the creation of political movements and not about the people who will be involved in politics,” he said. “That is an issue that we will have to deal with later.”

The government has said it will not release details about individual agreements until the entire process is complete. President Juan Manuel Santos has said he wants a peace deal by November, as he tries burnish the nation’s reputation as an emerging investment and tourism haven. But many think that date is too optimistic. It took negotiators six months to reach an agreement on the first point, and there are still contentious issues, including ending the conflict, the FARC’s role in drug trafficking, victims’ rights and how to implement a possible peace deal.