The French Senate has voted to block a referendum promised by President Emmanuel Macron on whether to enshrine the fight against climate change in the French constitution.
Mr Macron had pledged to organise such a vote in response to criticism that he has not done enough to protect the planet.
The Senate, the legislature's upper house, is dominated by the opposition conservatives. In May, it watered down draft legislation requiring the constitution to "guarantee" the fight against climate change, preferring less binding wording.
Right-wing politicians had expressed concerns that a state guarantee might become an obstacle to innovation and French business.
A group of centrist senators linked to Mr Macron's party said in a statement that the senate's vote definitively closes the door on holding a referendum.
"The conservatives in the Senate fail to understand the importance of environmental issues," the RDPI group said.
The clause's original wording had been proposed by a panel of 150 citizens established by Mr Macron to draw up policy proposals for battling climate change.
A referendum requires that the lower and upper house be in agreement.