French President Jacques Chirac was set to make a live television appearance Thursday in a bid to jumpstart the stumbling "yes" campaign for the European constitution, six weeks ahead of a May 29 referendum.

"Chirac's big oral exam," the conservative daily Le Figaro said of the debate, due to begin at 8:50 pm (1850 GMT). The popular France-Soir newspaper said: "Chirac Strikes Back".

Since mid-March, more than a dozen opinion polls have indicated that French voters will reject the landmark treaty in the May referendum. The most recent survey, published Thursday, put support for the 'no' camp at 55 percent.

"This is an extremely strong trend. It has transformed into a real hostility toward Europe, a concept that was unthinkable at the start of the campaign," Roland Cayrol, director of the CSA polling institute, told Le Parisien daily.

Chirac, who has staked his prestige on approval of the constitution, will launch his 'yes' campaign with a live two-hour evening debate with 80 young adults aged 18-30, handpicked from the 'yes', 'no' and undecided camps.

"Mission: impossible?" the influential Le Monde newspaper asked, saying that with Thursday's debate, Chirac would begin to tackle "one of the biggest challenges" of his political career.

"The campaign is now in its operational phase. The president's presentation will be essential," government spokesman Jean-Francois Cope said Wednesday.

The format of the show sparked controversy, as the main presenter, top news anchor Patrick Poivre d'Arvor, will be joined by three television talk show hosts, not journalists.

Those in the 'no' camp complained that Chirac would not face a political adversary, claiming the 'yes' campaign was getting preferential treatment in prime-time viewing hours.

But Chirac's aides quickly rejected those arguments, saying the president wanted to engage in a "direct dialogue with the French people", and that he would not debate other political leaders before the referendum.

Le Monde said in a commentary that while the high-stakes debate on private television network TF1 would not be "without risk" for Chirac, the show was "tailor-made" for him.

The constitution, which aims to streamline decision-making in the expanded 25-member European Union, must be ratified by all member states. A rejection in France, one of the EU's largest countries, would effectively kill the treaty.

The Elysee is banking on Chirac's ability to convince voters not to turn the referendum into a protest vote against the center-right government's gradual economic reforms, stubborn unemployment and decreasing purchasing power.

France's political heavyweights are also trying to hammer home the message that a 'no' vote could spark a crisis both at home and in the European Union, and also weaken the bloc's position with respect to the United States.

"A rejection would lead to a political earthquake in France," former European Commission president Jacques Delors told the Financial Times Deutschland.

"It would also weaken France's international position," he warned. "A 'no' would be a blow, both for Europe and for France."

French Foreign Minister Michel Barnier told reporters in the southern port city of Marseille that common European agricultural and regional policy would suffer if his country were to reject the constitution.

"This text marks progress, as compared with what Europe has today," Barnier said.

Liberation said in a commentary that Chirac's best weapon was to offer to resign if French voters approve the constitution, but acknowledged that such a scenario was unlikely.

"Deprived of this lethal weapon, all that Chirac has left tonight is the power of persuasion. Will he be able to find the words to convince people that the constitution is the best thing and a plus for Europe?" the paper asked.