By Will Grant
BBC News, Caracas
Losing at the polls has not been something that President Hugo Chavez of Venezuela has experienced since he was voted into office in 1998.
The battle will continue to bring reform, Mr Chavez says
Time and again, in both referendums and presidential elections, his supporters turned out in their droves to grant him a clear victory when opinion polls had predicted a close race or even a loss for the left-wing leader.
But this time, with his plans for a 21st Century socialist revolution laid out in front of the Venezuelan people, he suffered rejection - albeit by the slenderest of margins.
President Chavez's first move was to come on to state television and acknowledge the result. He also appealed for calm, wary perhaps of the violence that had marred the referendum campaigns.
Among the proposals that were rejected was a plan to shorten the working day and lower the voting age from 18 to 16.
There were also plans to alter the extent of the president's control over the military and remove the autonomy of the Venezuelan central bank.
But by far the most controversial measure was a proposal to grant the president the right to stand for re-election indefinitely.
Whether this was the point which caused traditional supporters to vote against the president is not clear.
One of the student leaders involved in mobilising the "No" campaign, Francisco Hernandez, told the BBC that the result represented a wider rejection of plans to take Venezuela towards a socialist state.
No campaigners celebrate but what will the opposition's strategy be?
"We believe strongly, those who voted against this constitution, that it would have excluded a large section of this country. The victory was only possible today because Chavistas (supporters of President Chavez) voted against these reforms," he said.
So where does this leave the president's plans?
Hugo Chavez still has almost complete control of the national assembly, has been granted the so-called "enabling law" for the next year, which allows him to pass legislation without recourse to parliament, and his current term runs until 2013.
And, of course, the price of oil, on which much of Venezuela's economy rests, is about $100 a barrel.
Mr Chavez remains steadfastly set on a course to further the reforms he has already put in place, which he and his supporters say have vastly improved the lives of the country's poor.
The referendum has undoubtedly been a blow to his plans.
But in his televised speech, President Chavez said that his plans were only derailed "for now" - in reference to the famous quote he made after leading a failed coup attempt in 1992.
"To me this is not a defeat," Mr Chavez said.
He would continue the battle to establish socialism in Venezuela, he said, and his proposals to reform the constitution remained "alive".