Colombia's government and the country's biggest leftist rebel group have reached a peace deal that puts the South American nation on the threshold of ending a five-decade war. Here's what lies ahead and some of the remaining hurdles:

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REFERENDUM ON PEACE

Colombians will get a chance to vote on the accord on Oct. 2. Although polls show approval is likely, the Revolutionary Armed Forces of Colombia is deeply unpopular and many voters may prefer a scenario that would allow them to seek revenge. The opposition also is likely to try to convert the vote into a referendum on Santos, whose approval rating is near the lowest it has been since he took office in 2010. Possible low voter turnout is also a concern because a minimum of 13 percent of the registered voters, or about 4.4 million people, must vote in favor for the accord to be ratified.

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REBEL CONGRESS

In the coming weeks, the FARC will hold its 10th and possibly final conference, in which top commanders will likely announce their decision to formally disband and create an unarmed political movement. Many rebels are wary of the government's guarantees it will boost protection. A similar peace attempt in the 1980s led to thousands of rebels and their sympathizers being killed by paramilitaries and corrupt soldiers.

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LAYING DOWN THEIR ARMS

A day after the still-unscheduled formal signing ceremony, Colombia's army will reposition troops to protect an estimated 7,000 rebel fighters as they move to 31 transition zones where 90 days later they will begin turning in their arms to United Nations-led monitors and begin the process of moving back into civilian life.

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CRIMINALITY

The overwhelming majority of Colombia's 11,585 homicides last year had nothing to do with the armed conflict. In fact, only four deaths in the past 13 months have been attributed to the FARC. There are concerns that as rebels integrate into civilian life, members of the heavily armed criminal gangs who already dominate large swaths of the countryside will fill the void and take over the drug-smuggling routes currently protected by the FARC.

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THE OTHER REBEL GROUP

There is a risk that Colombia's second rebel movement, the much-smaller but more recalcitrant National Liberation Army, could now expand its presence. That rebel group agreed only recently to formal negotiations with the government, but those talks have yet to start because of Santos' insistence that it renounce kidnapping, a main source of income for the group, which has rejected that precondition.

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LEGAL CHALLENGES

Negotiators have tried to bulletproof the deal against future legal challenges out of concerns it could unravel if a more conservative government succeeds President Juan Manuel Santos when he steps down in 2018. The provisions sparing guerrillas jail time if they confess their crimes could also be challenged at the International Criminal Court, which has yet to comment.