Far-right leader Marine Le Pen announced Monday that National Rally MPs would vote in favor of a no-confidence motion filed by the left-wing alliance Nupes in the French parliament, in a surprise move that spells trouble for French President Emmanuel Macron.

Both Le Pen’s National Rally and the left-wing bloc led by far-left leader Jean-Luc Mélenchon’s party filed separate motions of no confidence after the government used an emergency political mechanism to push through its 2023 budget last week.

“Because only the national interest guides its words and actions, the group I have the honor of chairing will also vote for the motion of censure presented in acceptable terms on the other side of the chamber,” Le Pen said in a speech at the National Assembly. “If tomorrow we have to go to the polls again, we are ready to do so”, she warned.

Both parties were keeping each other at arm’s length until now and had previously indicated that they would not vote for each other’s no-confidence motions — although Le Pen kept her options open.

The Nupes’ motion is unlikely to pass even with far-right support as their joint 240 votes still fall short of the required absolute majority of 289 votes needed to dismiss the French government. MPs from the conservative party Les Républicains, the third largest political group among opposition forces, have already announced that they won’t vote for the no-confidence motion.

But the unlikely opposition alliance is becoming increasingly dangerous for Macron just four months after the governing coalition lost an absolute majority in France’s parliamentary elections in June.