The demonstration occurred on the heels of strikes at oil refineries, adding to a tense political atmosphere.
PARIS — Tens of thousands of people marched in Paris on Sunday to protest rising living costs, amid an increasingly tense political atmosphere marked by strikes at oil refineries and nuclear plants that threaten to spread further.
The march had been planned long before the strikes by a coalition of left-wing parties eager to capitalize on the cost-of-living crisis and assert itself as the leading opposition force to President Emmanuel Macron. But on Sunday, organizers signaled that they intended to build momentum from the climate of social unrest to increase pressure on Mr. Macron’s government.
“We need to be tougher,” said David Guiraud, a lawmaker from France Unbowed, the hard-left party that led Sunday’s protest. He added that the government could “no longer decide on its own.”
Mr. Macron finds himself in a perilous situation. He is simultaneously facing discontent over shortages at gas stations, along with labor strikes and a fierce opposition in the National Assembly, the lower and more powerful house of Parliament, which may try to bring down his government this week over a disputed budget bill.
“We are entering a particular and quite extraordinary cycle,” said Jean-Luc Mélenchon, the leader of France Unbowed, as he led the protest on Sunday. He noted “the great convergence” among the strikes, the crisis in Parliament and the march.
At the heart of the matter are rising living costs. Already a key topic in this spring’s French presidential campaign, it has now moved to the top of French people’s concerns, according to a recent study, far ahead of more traditional issues like climate change, security or immigration.
Though lower than in the rest of Europe, inflation in France has surpassed 6 percent, jacking up the prices of staples like meat and pasta. Parliament passed an inflation relief package this summer, but it has not completely offset soaring energy costs, which are rising because of Russia’s war in Ukraine.
“It’s unbelievable,” said Gwenola Leroux, a 63-year-old retired literature professor, who marched on Sunday. “Every time I buy basic necessities, I wonder if they got the prices wrong.” She was holding a cardboard sign on which she had written a fable inspired by the 17th-century poet La Fontaine, denouncing inflation.
“Adieu, water, lettuce, saucisson, electricity,” it read.
The situation has been compounded by strikes at many refineries, which have left nearly a third of all gas pumps across the country fully or partly dry and have forced drivers to line up for hours at stations, sometimes in chaotic scenes.
Workers have been picketing for higher wages in line with inflation, as well as a greater share of the surging profits of energy giants. But their demands have resonated far beyond refineries, prompting nuclear plants and railroad workers to stop work, as well, or plan to.
The left has seemed eager to use the social unrest to bounce back politically from scandals involving domestic violence and harassment by prominent lawmakers. Members of France Unbowed have been trying to coalesce the discontent, with some traveling to strike sites in northern France to call for an amplification of the protests.
“You can count on us at the National Assembly to echo these fights, to carry your voice and to be at your side,” Thomas Portes, another France Unbowed lawmaker, told striking workers at a TotalEnergies refinery near Le Havre on Thursday.
Because of strategic disagreements, the main trade unions did not participate in Sunday’s march; they have instead called for a general strike next Tuesday. Mr. Mélenchon echoed that call on Sunday, describing the situation as the emergence of a “new Popular Front,” a reference to the broad leftist coalition that rose to power in France during the interwar period.
The march, which began at the Place de la Nation and ended at the Place de la Bastille, in eastern Paris, had all the hallmarks of a classic French leftist protest: a sea of red flags, antifascist slogans and booths selling revolutionary essays.
A participant stood out among the politicians leading the cortege: Annie Ernaux, this year’s winner of the Nobel Prize in Literature, who is an outspoken supporter of the left.
Several lawmakers said the march was meant to put pressure on the government as a high-risk week began in the National Assembly, where Mr. Macron no longer has an absolute majority.
The government faces a potential crisis over the contested budget bill. Debate on the measure has appeared to stall, with most of the opposition vowing not to vote for it. Mr. Macron’s government is likely to use special constitutional powers to get the bill through without a vote, possibly as soon as Monday.
But that mechanism would also allow members of the opposition to put forward a vote of no confidence. Although the risk of a government collapse appears remote because the center-right opposition seems reluctant to support the move, Mr. Guiraud, the France Unbowed lawmaker, confirmed on Sunday that the left-wing opposition in Parliament would present such a vote.
“We’re ready,” he said.