French Prime Minister Michel Barnier's government faces a critical challenge as far-right leader Marine Le Pen threatens a no-confidence vote in parliament unless the disputed draft budget meets her party's demands.

In a key demand, Le Pen's National Rally is demanding that pensions be reassessed.

The next few days could be decisive for the French government.

Just a few days ago, Barnier made a concession by waiving a tax increase on electricity.

But Le Pen is demanding new concessions. A no-confidence vote is "not inevitable" if Barnier agrees to negotiate with parliament on the draft, she told the Sunday edition of La Tribune newspaper.

Barnier, who has only been in office a few months at the helm of an uneasy center-right coalition, recently reminded television viewers that France is in debt to the tune of 3.2 billion euros ($3.4 billion) and needs to cut spending.

His minority government has introduced an austerity budget. Next year, the government aims to save 60 billion euros through savings and additional revenues.

On Monday, the bill on the financing of social security will be presented to the National Assembly.

Without a majority, the prime minister could opt for the application of Article 49.3 of the Constitution, a special constitutional power that allows for the authorization of a budget text without a vote.

However, he would risk the fall of the government if Le Pen's party were to unite with an alliance of left-wing parties.

The Barnier government is currently tolerated de facto by Le Pen's National Rally.