A No vote in the French referendum on the EU constitution would be "bad news" for the French and European economies, the EU Commission president has warned.
Jose Manuel Barroso says renegotiation is unlikely
Jose Manuel Barroso urged French voters to vote Yes in the 29 May vote.
Speaking on French radio, he said he agreed with the French prime minister that a No vote would affect the economy by creating uncertainty for investors.
Three recent opinion polls have showed the French No camp in front again, with up to 53% support.
Correspondents say Mr Barroso, is unpopular with some French voters, who regard his plans to make the EU more competitive as a threat to France's generous welfare state.
In March, President Jacques Chirac reportedly intervened to prevent him campaigning for a Yes vote on French television, on the grounds that it would be counter-productive.
'Sign of weakness'
Mr Barroso told Europe 1 radio: "Really it would be very bad news for the economy in France and Europe because investors want a scenario of confidence, many want certainties and security.
"Obviously a No would be a big question mark at the very least, if not a certain pessimism. Pessimism is bad for the economy. There would be more uncertainty and uncertainty in the economy is bad for consumption, it is bad for investment."
CHANGING FRENCH ATTITUDES
4 March: Voting date named14 April: Chirac TV debate28 April: Socialist ex-PM Lionel Jospin backs Yes in TV interview3 May: Chirac TV address16 May: Campaigns start29 May: Referendum day
He said France was a central country in the European project - and without France there would not have been a European Community.
"Everyone would be looking at the result of the referendum in France - both inside and outside Europe," he said.
"If, unfortunately, there were a No vote, this would be perceived as a sign of weakness in France and Europe."
The constitution has to be ratified by all 25 EU member states, only some of which are holding referendums.
The treaty is partly aimed at streamlining decision-making in the enlarged EU.
Mr Barroso said it was unlikely that the EU constitution would be renegotiated if there was a French No.
He said other European Union leaders had told him that, in the event of a No, "we should pursue the process".
"It would not be realistic to open a re-negotiation now."
He also warned of how the world outside Europe would perceive a French No.
"People would say: there you go, the Europeans are not able to agree on a constitutional treaty," he said.
"Twenty-five governments signed and they are not even capable of doing this. It would be very bad for the perception of our Europe, for the signs of confidence in it."
France's official campaign on the referendum opened on Monday, two weeks before the vote. The polls of about 1,000 people were conducted at the weekend.
The TNS Sofres/Unilog poll showed the No camp on 53%, with Yes on 47%. Two other polls - by Ipsos and CSA - showed the No camp on 51%, with Yes on 49%.
Correspondents say opinion may have been influenced by Monday's strikes, held to defy a government decision to scrap a traditional bank holiday.