• French lawmakers will debate and vote on the no-confidence motions filed against the fragile government of Michel Barnier on Wednesday.
• The government must step down if the either measure is approved by parliament, seen as a strong possibility if the left wing and far right unite.
• Attempts at compromise over the budget bill — which outlines 60 billion euros ($63.16 billion) in tax hikes and spending cuts to reduce France's deficit — stalled over the weekend.

French lawmakers will debate and vote on the no-confidence motions filed against the fragile government of Michel Barnier on Wednesday.

The motions, which have been tabled by the opposition left-wing bloc and by the far-right National Rally party, will be debated at around 4 p.m., the National Assembly said in a social media post.

The government must step down if the either measure is approved by parliament.

It comes after French Prime Minister Barnier on Monday opted to push through a highly-contested budget bill without parliamentary approval by deploying special constitutional powers.

The left and right are widely expected to be able to form an alliance to oust the current center-right government.

"Barnier is at the mercy of Marine Le Pen's right-wing Rassemblement National [National Rally]. Jointly with the united Left, she could topple Barnier in a no-confidence vote," Berenberg's Chief Economist Holger Schmieding warned in a note last week.

Attempts at compromise over the budget bill — which outlines 60 billion euros ($63.16 billion) in tax hikes and spending cuts to reduce France's deficit — stalled over the weekend.

It is unclear what will happen next, if the government is toppled. New parliamentary elections cannot be held until next June, 12 months after the last snap vote that was called by French President Emmanuel Macron this year.

Macron will also need to appoint a new prime minister — a politically charged task, given the fractured nature of the current parliament.

France's CAC 40 index was 0.57% higher after the Wednesday vote was confirmed, while the euro traded up 0.3% against the U.S. dollar. French bond yields were little changed.

Economists nonetheless say looming political instability could bring bad news for French assets, with the uncertainty already driving French borrowing costs to a 12-year high over those of Germany, and sitting at a level with those of Greece.

- CNBC's Holly Ellyatt contributed to this story.