Segolene Royal, who lost her bid to become France's first woman president, said Friday she planned to remain "very present" on the French political scene, though she did not specify in what capacity.
Royal is widely seen as a possible contender to succeed Francois Hollande, her romantic partner and father of her four children, as the head of the opposition Socialist Party.
She said she would remain "very present to continue the movement that started during this presidential election."
"I am regarded by public, by the electors as one of the leaders of the opposition," said Royal, though she declined to give any details about what role she might take. "I'm not ruling anything out."
Her former campaign director, Jean-Louis Bianco, said Friday that Royal will give up the seat she has held in parliament for 19 years. She will not run for re-election in her constituency in Deux-Sevres, western France, in parliamentary elections next month, he said.
Royal is also the president of the western region of Poitou-Charente, somewhat like a governorship. She spoke often during her campaign against politicians holding too many different posts at the same time, and pledged rules limiting such practices.
The parliamentary elections are seen as pivotal to the Socialists' efforts to stay united after their third straight presidential defeat and a series of setbacks in recent years.
Royal said she would "not make any statements that could disrupt the legislative" elections.
Sarkozy, keen to press ahead with reforms to labor laws and tax cuts, is hoping his conservative UMP party can retain its majority after the June 10 and 17 parliamentary elections. He takes over from President Jacques Chirac on Wednesday.