France's Emmanuel Macron vowed after stepping down as economy minister Tuesday to "transform" an ailing country but stopped short of declaring a presidential run.
The 38-year-old said he had "seen at first hand the limits of our political system" and that quitting the government of President Francois Hollande would enable him "to be free" to push forward his own agenda.
With elections eight months away, the former investment banker said: "I am determined to do everything so that our values, our ideas, our actions can transform France as soon as next year."
"I want to begin a new stage of my fight and build a project that serves the public interest," he said.
"We want this project to be for 2017, the country cannot wait," he said.
"The serious circumstances that our country is in, forces us to bring about change," he said in an interview on TF1 television.
But asked specifically about whether he would bid for the presidency next year Macron said: "We need to build this offer. Now is not the time for reincarnation.
"I have ambitions. I have a willingness to bring hope because our country needs it."
While Macron's resignation clears the way for a presidential bid, it is unclear how wide the appeal really is of such a young man who has never held elected office, nor does he have the support of a party.
An opinion survey last month nevertheless gave him a 41-percent approval rating.
On Tuesday Macron charged that France's political system is broken, and that his movement called "En Marche" (On the Move) would put forward a "diagnosis" of the country's woes next month.
Macron's departure is a blow to Hollande, whose approval ratings are the lowest of any post-war French president. He has pledged not to seek re-election if he fails to rein in stubbornly high unemployment, which is hovering at around 10 percent.
Hollande has said he will not decide on a re-election bid until the end of the year.
The embattled president, who has already alienated the left flank of the Socialist Party through economic and labour reforms, faces further isolation with the loss of the star of his government's centrist flank.
Macron would be a fresh face in a presidential field that includes former president Nicolas Sarkozy, 61, and 71-year-old ex-prime minister Alain Juppe -- both right-wing candidates.
Juppe is France's most popular politician, but Sarkozy is closing the gap fast. A poll this week showed both would score 34 percent in November's centre-right primary.
Marine Le Pen, 48, of the far-right anti-immigration National Front, is standing for a second time in presidential elections and many polls show she is likely to reach the second round of voting.
Macron, like most French politicians a graduate of the prestigious Ecole Nationale d'Administration, said he would "present the diagnosis of France drafted with the help of tens of thousands of people" at the end of September.
"I will then propose far-reaching action that can be taken," he said.