It is a crisis that has been waiting to happen, but was deferred till now by long procedural haggling over the 2025 budget.
Shortly after taking office in September, he proposed a budget that promised €60bn (£49bn) in deficit reduction – necessary, he said, to satisfy Brussels and get the country’s finances back in shape.
But because he lacked a majority, his budget was then disfigured by opposition amendments – from both left and populist right – which removed taxes and introduced more spending, thus changing its essential nature.
After much parliamentary to-ing and fro-ing with the conservative dominated Senate, Barnier came back with a new text, or technically texts, because there is a social security budget as well as the overall budget.
But that version remains unacceptable to the opposition.
Marine Le Pen, who could save Barnier if she chose to, made a series of new demands, including removing a new tax on electricity, and restoring fully index-linked pensions).
Barnier gave ground – quite a lot in fact. But it wasn’t enough. And now Le Pen plans to pull the plug.
Barnier and his supporters have made much of their one good argument – the chaos scenario.
What responsible party leader, they said, could want to tip France into the uncertainty and instability of yet another government crisis?