Eight Colombian presidents have tried and failed to make peace with the National Liberation Army (ELN). That includes the sitting president, Juan Manuel Santos, who was awarded the Nobel Peace Prize last year.

It remained far from clear in recent weeks whether talks, already postponed several times, would take place. Only the release of Odin Sanchez,  a former congressman, on February 2 cleared the path to the next round of dialogue, which is set to begin in earnest on Tuesday in Ecuador.

The ELN is the country's largest guerrilla movement after the Revolutionary Armed Forces of Colombia (FARC), but it is organized differently, said Hubert Gehring, the head of the Bogota office for the Konrad Adenauer Foundation. Unlike FARC, the ELN is decentralized. The peace deal with FARC led to the disarming of 95 percent of its combatants. The same may not transpire for the ELN's 1,400-member force.

The group was founded in 1964 by Camilo Torres, a Colombian priest and follower of liberation theology, as a mix of Marxism, Catholicism and nationalism. The movement has no interest in becoming a political party, but wants the Colombian people to be part of decision-making.

'Communist clergy'

Even today, the ELN maintains a strong connection to the Catholic Church. Dario de Jesus Monsalve is the archbishop of Cali and the talks' coordinator on behalf of the Episcopal Conference of Colombia.

"Monsalve serves as an important door opener during negotiations," said Thomas Wieland, Colombia project leader for Adveniat, an episcopal relief organization for Latin America that trains pastors in areas where onetime combatants have disarmed. "The ELN requested that the church be part of the peace process."

The archbishop's involvement has put him in danger. Monsalve has received death threats for months, including a flier stuck under his door in Cali in December with the warning "Death to FARC, Santos and the communist clergy."

The peace process with ELN began four years ago, and negotiations have taken place in five countries. "This requires a great deal of logistics and at great expense," Wieland said. "Additionally, the people should be more closely involved."

The two sides

The ELN and Colombia's government have yet to decide in detail the exact points to be negotiated. The government's chief negotiator is Juan Camilo Restrepo, the former agriculture minister. Israel Ramirez Pineda, known as Pablo Beltran, is representing the ELN in Quito, the capital of Ecuador. He is a 63-year-old chemical engineer and one of the group's five commanders - and thought to be responsible for a number of kidnappings.

The first order of business is how best to involve Colombians in both the negotiations and in implementing the resulting agreement. Political reform, care for victims and the ELN's demobilization are all on the table.

It is difficult to assess whether Colombians even want to be part of the process, however. The ELN is roundly hated for the numerous abductions and attacks on energy pipelines that it has conducted over the years. The "massacre in Machuca" is particularly painful in Colombia's collective memory. On October 18, 1998, ELN fighters blew up an oil pipeline. The resulting fire killed 84 people, half of whom were children.

Is ELN committed?

The kidnappings continue. On January 24, the soldier Fredy Mahecha Morena was abducted in Arauca, a state on the border with Venezuela where the ELN remains strong. He was released Monday, thanks in part to a flurry of media attention.

Talks could falter on any number of points, including how open the ELN will be to accountability for its crimes and whether it is prepared to disarm. Restrepo, the government's chief negotiator, has already said the ELN will receive the same terms afforded to FARC in its disarmament negotiations. Opponents of the FARC deal have criticized those terms of prosecution as too lenient.

"Out of fairness and special justice, Colombia cannot afford to proceed with something different for the ELN than what it did for FARC," the Adenauer Foundation's Gehring said. That could jeopardize the deal with FARC, as well. The government's most important task is to invest in the country's remote regions to improve living conditions there, he said.

"In Choco or Arauca, people still live under feudal conditions and guerrillas have taken over public functions in light of the power vacuum," Gehring added. "Nothing will change so long as the state is not present everywhere - regardless of how many peace treaties are signed."