PARIS -- French Prime Minister Sebastien Lecornu resigned Monday after less than a month in office, making him the shortest-serving prime minister of France's Fifth Republic. President Emmanuel Macron accepted his resignation, the presidency said.

In a statement, Lecornu admitted the formation of his government had not gone smoothly, saying conditions "were no longer met" for him to remain in office. "One must always put one's country before one's party," he said, adding that the cabinet's composition had stirred partisan tensions.

Explaining his decision, Lecornu said he had sought consensus by consulting parties and trade unions before presenting his cabinet, and pledged not to use a constitutional tool to bypass parliament on budget bills. But he admitted the move failed to win wider support.

The decision rattled investors, with the CAC 40 index opening 2 percent lower on Monday following news of his departure.

Lecornu, appointed 27 days ago, quit a day after unveiling a cabinet lineup that was nearly identical to its predecessor and drew sharp criticism across the political spectrum. French media reported the "virtually unchanged" government was expected to face a censure motion in parliament.

Lecornu's resignation triggered emergency meetings across the political spectrum. Marine Le Pen, leader of the far-right National Rally (RN), again called for the dissolution of parliament.