Michel Barnier faces immediate vote of no-confidence amid fury over Macron's appointment

However, the appointment has already angered politicians on the left, who maintain that the head of government should reflect French voters' clear preference for the leftist New Popular Front.

The Brexit hardliner now faces an immediate vote of no confidence with accusations from the French left as to a lack of democratic legitimacy.

Speaking in the courtyard of the Matignon prime minister's residence, Barnier said his tenure "will be about addressing, as much as we can, the challenges, the anger, the suffering, the feeling of abandonment, of injustice running through many of our cities, suburbs and rural areas."

At 73, Barnier is the oldest prime minister in France's modern political history, taking over from Gabriel Attal, who was the youngest. It took Macron two months to appoint him after the election failed to give any group a clear majority.

Barnier said he would listen to all political groups, citing health care, security and jobs as well as reducing the country's excessive debt as priorities.

He said: "The French...expressed their need for respect, unity and appeasement."

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Hard-left leader Jean-Luc Melenchon said: "The election was stolen from the French people" while another hard-left lawmaker, Mathilde Panot, called it an "unacceptable democratic coup."

Jordan Bardella, the president of the Marine Le Pen's far-right National Rally (RN), parliament's biggest single party, demanded the hard-right's concerns be addressed. He said: "We reserve all political means of action if this is not the case in the coming weeks."

The fates of Barnier and Macron rest with RN which gave tentative support to Barnier's nomination.

But the party made clear it could withdraw support at any point if its concerns on immigration, security and pocketbook issues are not met.

Barnier is a pro-European and moderate career politician, though he toughened his discourse considerably when he unsuccessfully sought his party's presidential nomination in 2021, saying immigration was out of control.

He became a lawmaker at age 27 and served in several French governments, including as Foreign Minister and Agriculture Minister.

He has spent most of the past 15 years working at EU headquarters in Brussels, where he led the EU's talks with Britain over its exit from the bloc.