The Republicans were mauled in the last presidential elections in 2017, when Mr Macron poached some of their top figures, naming them interior, finance and prime minister, and swathes of their electorate.

“The Right is back”, Ms Pécresse intoned in her first speech as official candidate, in which she promised to “restore French pride” with a programme of budget cuts, immigration curbs, a defence of “family values” and a crackdown on crime, focusing as much on economic rigour as on security concerns.

It includes harsher rules on nationality and welfare and plans to send the army into no-go zones in the banlieues, or suburbs, where she has pledged to get the “power hose out of the cellar” to clean up crime.

She claims to have brought her region’s finances under control, while accusing Mr Macron of “burning up the till” with unrestrained spending that has worsened France’s debt load.

She also wants to “save” France’s generous state pension scheme by pushing back the legal retirement age on a full pension from 62 to 65.

On foreign policy, Ms Pecresse has said she is against the EU becoming a federal superstate.

“I hear some of our German partners suggest that the European Union should evolve into a federal state,” she said recently. “Politely, but firmly, I will say ‘no’.”

Polls suggest the Right-winger is the only candidate who currently stands a chance of beating Mr Macron should she reach the second-round runoff, a feat far from assured given polls often placing her in fourth or fifth place in round one.

Crucially, she needs to sway a sizeable chunk of the electorate that voted for her party predecessor François Fillon, who scored 20 per cent in the first presidential round in 2017 despite being mired in a fake jobs scandal. Some Fillon supporters now back Mr Macron, others – many Catholic traditionalists – Mr Zemmour.

“We need to go and get them on both sides,” said conservative MP Eric Pauget.

The way to do so, Vincent Chriqui, co-author of her manifesto, told Le Monde, is by proving “she has a real project for economic reform and radical measures on crime and immigration”.

However, polls suggest she has a mountain to climb to reach the runoff.

Political analyst Jean-Yves Camus, said: “The real earthquake on the evening of the first round will be if (she) musters only 10 per cent and finishes behind Eric Zemmour. That could well spell the end of the Republicans Party.

“France is one of the very rare countries in Europe, perhaps the only one, in which the mainstream conservative party is such a parlous state,” he said.