Macron, a 43-year-old centrist, has promised a referendum on making the fight against global warming a legal duty after it was urged by his Citizen’s Convention on Climate last year.
The convention was set up to respond to demands by ‘yellow vest’ anti-government protestors for greater direct democracy.
The delegates came up with 149 proposals, which form the backbone of a sweeping environmental protection law currently making its way through parliament.
The proposals included adding the environment to the first article of the constitution, which set out the founding principles of the French republic.
The government has suggested adding a clause stating that France “guarantees environmental protection and biological diversity, and combats climate change.”
But while the revision is likely to pass Tuesday’s vote in the Assemblée nationale, where Macron has a majority, it faces a tougher fight in the upper-house Senate, where the rightwing Republicains hold the majority.
Opponents on the right fear a constitutional clause would discourage private enterprise and have called to replace the word “guarantees” with less restrictive phrasing.
Far-right leader Marine Le Pen, whom polls show as the biggest threat to Macron in next year’s vote, denounced the proposed clause as “political posturing” while presenting her own environmental plan last week.
Leftwing parties and NGOs also accused the president of trying to score a PR victory.
They pushed unsuccessfully for a principle of “non-regression” that would prohibit any softening of environmental laws.
Under French law, a referendum can be submitted to a vote only if it is approved in identical wording by both houses of parliament.
But the vote could prove risky for Macron if voters use it to express broader discontent with the president’s leadership.
The last referendum in France was in 2005, when voters were asked to back the creation of a European constitution, which was rejected in a humiliating defeat for then president Jacques Chirac.