Marine Le Pen’s ultimatum to French Prime Minister Michel Barnier, even after he caved on a key demand from her party, lays bare the unprecedented clout the far-right leader now wields in Paris’ halls of power.

To survive the vote in the fractured lower house, Barnier needs Marine Le Pen's party to abstain, otherwise his government and the budget bill could fall, plunging France into a political crisis.

When the prime minister was appointed in September, Ms Le Pen pledged not to vote against his government right away. But she offered no more support than that. As the budget has wound its way through parliament,

Far-right leader Marine Le Pen, who holds outsize leverage in France’s split parliament, gave Prime Minister Michel Barnier until Monday to adhere to her budget red lines before she decides whether to topple the government.