French Economy Minister Emmanuel Macron has resigned from government, the French president's office said on Tuesday, adding that Finance Minister Michel Sapin would take over the portfolio together with his current finance role.
A run by the man polls say is the most-liked minister in Francois Hollande's government would further weaken the president's chance of re-election and add to the uncertainty of a race where the far-right National Front is a bigger threat than ever to the mainstream parties.
The 38-year-old former investment banker's place in the Socialist government has become increasingly awkward since Macron created his own political movement in April, casting it as leaning neither left nor right.
A source in Macron's inner circle said the rapidly evolving political situation, in which former president Nicolas Sarkozy and two former Socialist ministers had declared their intention to run for president, had forced the minister's hand.
"We were originally going to wait until Sept. 15 to take decisions, but the political environment has been so lively that he has to stake out his position," the source told Reuters.
Macron, who has earned a reputation as a maverick by attacking pillars of France's social model like its 35-hour work week, has stage-managed suspense about his presidential ambitions.
He has repeatedly refused to confirm or deny whether he would run in the two-round election next April and May but told supporters at a rally in July he would carry them "to victory" next year.
Macron has won plaudits from economists and business leaders by pushing through a deregulation law cutting red tape for retailers and the legal profession among other areas.
But while at ease on economic issues, he is untested on security in a country where a string of Islamist attacks has made law and order and immigration key vote winners, with Sarkozy vowing to ban the "burkini" full-body swimwear across France if returned to the top job.
Macron ranks in polls just behind former prime minister Alain Juppe, a centre-right presidential contender, but analysts say that popularity may not equal votes.
"He needs to transform his considerable popularity into voting intentions, but it won't be easy because he's not well liked on the left and his popularity on the right would not necessarily translate into votes," said IFOP pollsters' analyst Frederic Dabi.
As well as weakening Hollande, a Macron bid could hurt Juppe's chances, as both would target centrists. Juppe must first beat Sarkozy in what promises to be a bruising fight at the conservative Les Republicains' primaries in November.
Others on the left are challenging Hollande, including more hardline Socialists such as former industry minister Arnaud Montebourg and ex-education minister Benoit Hamon.