French Socialist MPs and supporters have started to break ranks with their party after the primary election win of leftwing presidential nominee Benoît Hamon, offering support to independent candidate Emmanuel Macron.

Hours after Mr Hamon won the Socialist nomination with 59 per cent of the vote, a handful of figures from the party’s business-friendly wing said they would not back the nominee, who opposed President François Hollande’s reforms and wants a clean break with his pro-business policies.

The fissures on the French left after Mr Hamon’s win add to a sense of political upheaval just three months before presidential elections that are set to be closely contested.

While far-right leader Marine Le Pen is predicted with near certainty to qualify for the runoff in May, François Fillon, the centre-right candidate, and centrist Mr Macron are now neck and neck for second place, according to polls.

Alain Calmette, an MP from Cantal, central France, said on Sunday evening that it was “impossible” for him to back Mr Hamon “without disowning all my votes in parliament during [Mr Hollande’s] presidency”. Mr Calmette said he considered himself a “Macrono-Vallsist”, highlighting the similar social democratic views of former prime minister Manuel Valls, who lost to Mr Hamon on Sunday, and Mr Macron.

Other Socialist MPs also said they would not support Mr Hamon. Leading Socialist figure Pierre Bergé, the industrialist, long-time partner of Yves Saint Laurent and major shareholder in the daily newspaper Le Monde, tweeted his support for Mr Macron on Monday. A “reformist” group of MPs led by Gilles Savary, from southwestern France, is also expected to express their support for Mr Macron on Tuesday.

The left is holding its head high again

Mr Hamon’s nomination highlights a desire among French Socialists to return to core leftwing policies after Mr Hollande’s unpopular presidency. The former education minister, 49, left Mr Valls’ government in 2014 because he disagreed with its supply-side policies. He then led a rebellion in parliament against the government’s jobs bill.

“The left is holding its head high again,” Mr Hamon told supporters on Sunday. “I want to unite the French around a desirable future.”

Mr Hamon’s flagship policy is the introduction of a monthly universal income of about €750, a measure that would cost €400bn a year, and would be partly financed by a tax on robots. Mr Hamon also supports increased public spending and a wider fiscal deficit to support more investment in renewable energy. Mr Valls attacked the measures as “illusory” and lacking credibility.

With polls suggesting likely defeat in the first round of presidential elections as well as in June legislative elections, Mr Hamon will struggle to mollify party centrists who want to rid the party of its Marxist influence and prove its fitness to govern by embracing globalisation and the need for budget discipline.

Mr Hamon said he would seek an alliance with Jean-Luc Mélenchon, the far-left leader who is projected to attract between 10 and 15 per cent of the votes in the presidential election.

Mr Macron has emerged as the third candidate in presidential polls behind Ms Le Pen and Mr Fillon. But a survey by Kantar Sofres released on Sunday suggested that Mr Fillon, the centre-right candidate, may be losing momentum after a controversy over payments to his wife. The survey suggested Mr Fillon would attract 22 per cent in the survey — 1 point ahead of Mr Macron. Ms Le Pen is projected to secure 25 per cent of the vote.

While splits in Socialist ranks appear to open up more opportunities for Mr Macron, he may not welcome Socialist defectors, since his campaign is partly based on his portraying himself as a political outsider. Mr Macron has warned that there would be no guarantee that Socialist MPs could represent his party En Marche in legislative elections.