BOGOTA Colombias government and Marxist FARC guerrillas will scramble on Monday to revive a plan to end their 52-year war after voters rejected the hard-negotiated deal as too lenient on the rebels in a shock result that plunged the nation into uncertainty.

Putting on a brave face after a major political defeat, President Juan Manuel Santos offered hope to those who backed his four-year peace negotiation with the Revolutionary Armed Forces of Colombia (FARC) in Cuba.

Latin Americas longest conflict has killed 220,000 people.

I will not give up, I will keep seeking peace until the last minute of my term, he said moments after losing Sundays plebiscite to those who want a re-negotiation of the deal or an obliteration of the FARC on the battlefield.

Santos, whose term ends mid-2018, plans to meet all political parties on Monday.

He is also sending lead government peace negotiator Humberto de la Calle back to Havana to speak to the FARC leadership.

Rodrigo Londono, the top FARC commander better known by his nom de guerre Timochenko, also offered reassurance the rebels remain committed to becoming a peaceful political party.

The FARC reiterates its disposition to use only words as a weapon to build toward the future, Timochenko said after the result. Count on us, peace will triumph.

Disappointed Latin American neighbors urged Colombia not to give up on peace. With Chile, Cuba, and Venezuela acting as guarantors and observers of the negotiations in Havana, the region had been closely involved with the deal.

Were saddened by the slim victory for No, said Ecuadors Foreign Minister Guillaume Long, after the peace deal was rejected by a razor-thin margin of less than half a percentage point or only 54,000 votes.

Colombia must keep seeking the road to peace.

Following the result, peace researchers dropped Colombia from a list of favorites for the Nobel Peace Prize.

Santos, 65, who was not obliged by law to hold a plebiscite, had said there was no Plan B for the failure of the peace vote, but now appears ready to consider options.

Turnout for the vote was a paltry 37 percent, reflecting some apathy from yes supporters who had assumed an easy win plus bad weather that deterred voters on the day.

Colombians, even those who backed the No vote, expressed shock at the outcome and uncertainty about the future.

We never thought this could happen, said sociologist and No voter Mabel Castano, 37. Now I just hope the government, the opposition and the FARC come up with something intelligent that includes us all.

The peace accord reached last month and signed a week ago offered the possibility that rebel fighters would hand in their weapons to the United Nations, confess their crimes and form a political party rooted in their Marxist ideology.

SIXTIES ROOTS

The FARC, which began as a peasant revolt in 1964, would have been able to compete in the 2018 presidential and legislative elections and have 10 unelected congressional seats guaranteed through 2026.

That enraged No supporters, including powerful former president Alvaro Uribe, who argued the rebels should serve jail terms and never be permitted to enter politics.

Uribe, a onetime ally who has become Santos fiercest critic, may now hold the key to any potential re-negotiation.

While the FARC has refused to serve traditional jail terms, it may see no future in returning to the battlefields and so consider some sort of new deal.

In the end, the people have spoken: the Colombian government and the FARC have no choice but to renegotiate, said Peter Schechter, director of the Adrienne Arsht Latin America Center.

The FARC already softened its stance in the original negotiation, publicly admitting for the first time it trafficked drugs, recruited minors and committed human rights violations, including massacres.

But voters worried the rebels would not turn over assets from drugs and illegal mining, potentially giving them a formidable war chest that could outstrip the coffers of traditional parties.

Regions still riven by the conflict, including poor areas along the Pacific and Caribbean coasts, voted resoundingly in favor of the deal, but formerly violent interior areas pacified during the Uribe presidency largely backed the no camp.

How sad. It seems Colombia has forgotten about the cruelty of war, our deaths, our injured, our mutilated, our victims and the suffering weve all lived through with this war, said Adriana Rivera, 43, a philosophy professor standing tearfully at the hotel housing the headquarters of the yes campaign.

The vote may delay Santos plans to move on to other matters including much-needed tax reform and other measures to offset a drop in oil income. It will also dent his hopes for a boom in foreign investment in mining, oil and agriculture in Latin Americas fourth-largest economy.

Colombias financial markets were expected to react negatively. Goldman Sachs analyst Albert Ramos said a weaker peso currency and political uncertainty would probably limit the central banks ability to cut interest rates in the short-term.

The victory of the No camp is likely to render Colombias domestic political picture even more complex and could impact the tax proposal the government was expected to announce soon after the referendum, he added in a note to clients.