France was reeling last night from a double political shock. The defeated presidential candidate, Ségolène Royal announced that she had ended her 27-year relationship with the Socialist party leader, François Hollande.

The announcement came just after the French people rebuffed President Nicolas Sarkozy, denying him the landslide victory that he had confidently expected in the French parliamentary elections.

Mme Royal, 53, chose the end of the long French electoral season to confirm dramatically the persistent rumours of a rift in her long, unmarried relationship with M. Hollande. She said that she had "asked him to leave the home" and that she would be a candidate to replace him as the Socialist Party first secretary next year. The couple have four children, aged 15 to 24.

In a book to appear on Wednesday, Mme Royal will, in effect, confirm rumours that M. Hollande has been in a relationship with another woman. "I have asked François Hollande to leave the family home and to continue alone the romantic life, which will now be plastered all over the books and newspapers. I have wished him every happiness," Mme Royal says in the book, Corridors of a defeat, by Christine Courcol and Thierry Masure.

The announcement came just as M. Hollande and the Socialist Party were celebrating a relative triumph in the second round of the parliamentary elections.