Francois Hollande has announced he will not seek a second term as France's president.
Mr Hollande, in a TV address to the nation from the Elysee Palace, said he would serve out the remainder of his term until May before handing over to his successor.
His Socialist Party will pick its candidate in January primaries.
Mr Hollande's term has been overshadowed by terror attacks that claimed hundreds of lives and forced him to declare a state of emergency.
"I have decided not to be a candidate to the renewal of my mandate," said Mr Hollande, who becomes the first president in modern times not to seek a second term.
"In the months to come my sole duty will be to continue to lead the state, the mandate for which you elected me in 2012."
Current polling does not make good reading for France's centre-left, with the centre-right resurgent under newly-selected candidate Francois Fillon and the far-right Front National having made large strides under leader Marine Le Pen.
Mr Fillon, a 62-year-old father-of-five whose Welsh wife is from Abergavenny, did not wait long to take aim at the man he hopes to succeed in May.
He tweeted: "This evening, the President of the Republic admits with lucidity, that his patent failure prevents him from going on further.
"This five-year term is ending in a political mess and the dissolving of power."
Mr Hollande's prime minister Manuel Valls, who may seek the Socialist nomination, said the decision by his boss was "of a statesman".
Mr Hollande's victory over incumbent Nicolas Sarkozy in 2012 ended a 17-year reign at the Elysee Palace for the centre-right which endorsed Mr Fillon as candidate with its own primary process which ended last Sunday.
Mr Fillon, a former prime minister, had surprised his centre-right rivals, seeing off Mr Sarkozy and another former prime minister Alain Juppe to win the nomination for the movement now known as Les Republicains.
Ms Le Pen came third in 2012 with 17.9% of the vote but has seen her poll ratings climb with voters more receptive to hardline security and immigration policies in the wake of the massacres in Paris and Nice that have blighted Mr Hollande's spell in power.
Polls carried out before Mr Hollande's decision to withdraw suggested that Mr Fillon and Ms Le Pen were the two likely candidates to progress to the second decisive round of next year's presidential election on May 7.
The first round of the presidential election itself will be held on April 23 when a larger field will be whittled down to two.