French media gave President Jacques Chirac poor marks yesterday for his effort to promote the European Union Constitution in a live television debate, and campaigners for a "No" vote accused him of scaremongering.

Mr Chirac told voters in the prime-time broadcast on Thursday evening that France could "cease to exist politically" in the EU if they reject the charter in a referendum on May 29.

The debate marked the start of Mr Chirac's push to promote the Constitution. The conservative government had hoped he could help reverse the "No" campaign's lead in opinion polls but French media said he was unconvincing.

"In front of an audience in which those favouring the 'No' seemed to be in the majority, the head of state often struggled to make heard his pro-European plea during a muddled broadcast," the conservative newspaper Le Figaro wrote on its front page.

"Chirac: difficulty reassuring," LCI television said in a caption. The left-leaning Liberation newspaper said Mr Chirac appeared "strained, almost clenched-up" during the debate.

The Constitution is intended to make EU decision-making easier following the admission of 10 new members last May. Its rejection could cause a crisis at the heart of the union because the treaty requires the approval of all 25 EU member states.

Mr Chirac mixed warnings of dire consequences and gentle lecturing on the content of the Constitution in the debate with 83 young people.

Laurent Fabius, a former Socialist Prime Minister and leading "No" campaigner, accused Mr Chirac of trying to frighten voters into backing the charter.

"I found Mr Chirac, like the Constitution, long and not very convincing," he told RTL radio. "I was very struck to see Mr Chirac saying on the one hand, 'don't be afraid', but his main argument was to try to create fear."

Mr Chirac said the treaty could not be renegotiated if voters reject it but that he would not resign over the charter, on which he has staked his personal prestige.

Opinion polls show the anti-treaty campaign is clearly ahead just six weeks before the referendum. The surveys point to deep discontent with high unemployment and with France's declining influence in Europe.

Education Minister Francois Fillon said Mr Chirac had been convincing in the debate with the young people and that it was a tough examination.

"It was much harder for the President than a debate with journalists," Mr Fillon said.