The TNS-Sofres-Unilog poll for the RTL radio station indicated 52 percent of decided voters would back the constitution in the May 29 referendum.  

However nearly a quarter of the 1,000 people quizzed said they had still not made up their minds.  

In recent days three opinion polls have shown the ‘no’ lead dropping from a high of 58 percent on April 21, as alarmed top French and European politicians scrambled to secure the constitution’s future.  

If such a heavyweight EU member as France rejects the constitution many observers believe it will effectively be killed off.  

The latest poll was taken after an unsuccessful television appearance by French President Jacques Chirac but before an intervention Thursday night by former Socialist prime minister Lionel Jospin urging a ‘yes’ vote.  

But it showed that supporters of the divided opposition Socialist Party were changing their minds, with only 51 percent against the constitution, against 63 percent in a survey by the same organisation published on April 20.  

All 25 states have to approve the constitution for it to come into effect.  

So far six of the 25 EU member states have done so, by referendum or votes in their respective parliaments. France’s referendum on May 29 will be followed by the Netherlands on June 1.  

The Dutch are also on a knife edge but unlike the French their referendum is consultative and not binding for the government.  

Other EU states including Luxembourg, Denmark and Portugal appear determined to hold their referendums whatever the result of the French vote. There have been suggestions that Britain and Poland may reconsider.