France's main left-wing party was on the brink of implosion yesterday after former prime minister Manuel Valls backed independent front-runner Emmanuel Macron in next month's presidential election instead of his own Socialist Party's candidate.
Mr Valls (54), a reformist once likened to Tony Blair, is the highest-profile Socialist yet to say he will vote for the 39-year-old Mr Macron.
The centrist was, he said, the best hope to foil the rise of the far right, as Mr Macron is polling to beat the Front National's Marine Le Pen in the election's second round run-off on May 7.
Benoit Hamon (49), the Socialists' official candidate, beat Mr Valls in the party's primary but is predicted to finish a humiliating fifth in the first round of the election on April 23.
"I'm not going to take any risks," Mr Valls told BFM TV, warning that the Le Pen vote risked being higher than expected. "I will vote for Emmanuel Macron."
The Hamon camp was livid, branding Mr Valls a dishonourable traitor because he had signed a promise to back the winner of the Socialist primary.
"I urge you to sanction those who have started this morbid game... those who no longer believe in anything," Mr Hamon said.
Mr Valls, a centrist within Socialist ranks who was President Francois Hollande's prime minister until he stood down to contest the presidential nomination, is not the first Socialist heavyweight to betray Mr Hamon.
Jean-Yves Le Drian, the defence minister, did so last week. Around 50 other Socialist lawmakers have also said they will support Mr Macron's party, En Marche!, which he set up last year, and more government figures are expected to follow suit.
This, however, poses a conundrum for Mr Macron, a former economy minister in Mr Hollande's government whose appeal is largely based on his claim to be a new type of politician who is "neither right nor left wing".
Mr Macron was quick to make it clear Mr Valls would not be part of his government. "I shall be the guarantor of new faces, new ways of doing things," he said.
Mr Valls said he had "nothing to negotiate and am not asking for anything, I'm not joining his camp".
But the move prompted Francois Fillon (63), the embattled conservative candidate, to brand Mr Macron a Mr Hollande clone.
"The entire team of Francois Hollande now backs Emmanuel Macron. It is as I have always said: Emmanuel Macron is Francois Hollande," Mr Fillon, whose British wife was placed under investigation in a fake jobs inquiry on Tuesday, said.
Polls suggest that for the first time, neither France's largest centre-right nor centre-left political movements will have a candidate in the presidential run-off.
Mr Valls's departure is the latest blow for Mr Hamon who is vying for the left-wing vote with charismatic former Trotskyite Jean-Luc Melenchon.
A poll yesterday suggested Mr Hamon would reap just 10pc of the vote in round one, with Mr Melenchon, who refuses to join forces, on 15 per cent.
His spokesman gleefully tweeted: "Valls rallying to Macron spells the explosion of the Socialist Party. A new situation commences." (© Daily Telegraph, London)