Francois Hollande is facing the toughest hour of his presidency as his partner remains in hospital after news of his alleged affair with a glamorous actress.
The French President was to hold a high-profile press conference overnight, initially expected to climax with a key announcement on reforms to spur economic growth and create jobs.
Hollande, 59, planned to float his "responsibility pact", in which he offers firms lower labour taxes in exchange for hiring more staff.
But the conference was more likely to produce headlines on Hollande's private life, which was thrust into the spotlight last week by media claims he was having an affair with Julie Gayet.
The Leader of the Opposition, UMP party chief Jean-Francois Cope, has already pounced on the scandal as "having deeply undermined the President's authority".
David Assouline, a spokesman for Hollande's Socialist Party, stressed the right of any public official to a private life.
Hollande's hopes of riding out the storm were shattered with the hospitalisation of Valerie Trierweiler, his companion of several years and de facto first lady. She had been expected to check out yesterday, but "doctors believe she needs more rest", an aide said.
Symptoms variously described in the media as low blood pressure, exhaustion and a "severe case of the blues" developed within hours of glossy French magazine Closer publishing details of Hollande's alleged secret trysts with Gayet in a borrowed apartment close to his residence.
"He has to clarify the situation," said Thierry Mandon, speaking for the Socialist Party's parliamentary group. "He has to do it once, firmly and decisively, and then we don't talk about it any more."
Despite concerns that Hollande had apparently been taking risks with his own security with clandestine visits to the flat on a chauffeur-driven scooter, it looked as if he would be allowed to resolve his personal dilemma behind closed doors. But the fact that Trierweiler is effectively a public figure with an entourage funded by the taxpayer has made her future a legitimate news story.
Yesterday, Le Parisien, quoting a "close friend", reported that Trierweiler had no intention of immediately ending her relationship with Hollande.
Frederic Gerschel, a reporter who spoke to Trierweiler on Monday, said she learned of the affair on Friday when Hollande told her. It was a huge shock.
"Naturally, she couldn't ignore the rumours that swirled around Paris in the past few weeks. She simply chose to believe they were false. For her, they have always formed a couple."
Despite the meetings Closer said Hollande had with Gayet, a friend said he and Trierweiler "absolutely didn't live in separate wings of the Elysee as some have said". The source also quashed rumours that Trierweiler had tried to commit suicide. She had been taken to hospital as a "preventive measure" and her doctor had prescribed her "10 days of rest" because of stress and low blood pressure, the newspaper said.
Meanwhile, the photographer who took the pictures with the Closer article said the President's security detail left once Hollande went inside the building where he met Gayet, and that they did not return until the next morning.
Sebastien Valiela told RTL radio it would have been easy to try to attack the President.
- additional reporting AFP