PARIS — Newly appointed Prime Minister Sébastien Lecornu will have to hit the ground running, taking the reins of government just as protesters seek to bring France to a grinding halt.

Authorities are bracing for demonstrations and blockades on highways, train stations, airports and refineries as part of an online movement called “Block Everything.” Paris Police Chief Laurent Nuñez said an “exceptional” deployment of close to 80,000 security forces across the country is planned for Wednesday and that authorities will “intervene systematically” to remove any blockades.

The shutdown campaign began gaining steam after outgoing Prime Minister François Bayrou unveiled his plans to squeeze the 2026 French budget by €43.8 billion in July.

Lawmakers on Monday torpedoed Bayrou’s government over those spending plans, which the longtime centrist argued were necessary to rein in excessive public spending.

The French president appointed Lecornu a day after Bayrou’s downfall, responding to calls quickly replace the outgoing prime minister at a time of deep political tension. Interior Minister Bruno Retailleau himself called on the president to fill “the power vacuum.”

The scale of the unrest will be a major test for Lecornu, one of Macron’s closest allies since he came to power, and the former armed forces minister will see his authority and popularity tested on his first day on the job. A discreet political operator, Lecornu has earned plaudits for shepherding France’s rearmament in the wake of the war in Ukraine, but will be thrust in the limelight like never before.

In addition to responding to any violence during Wednesday’s protests, Lecornu will have to jumpstart budget talks through a paralyzed parliament without a majority.

And even more widespread strikes are planned for next week.

‘No organizers, no one we can talk to’

In addition to its big security rollout on Wednesday, the French government is also investigating whether foreign agitators attempted to amplify the movement, though one official said the effect had so far been “marginal.”

While comparisons have been drawn between “Block Everything” and the Yellow Jackets, an analysis by the Jean Jaurès Foundation concluded that the two movements are “profoundly different,” with Wednesday’s plans driven in large part by the radical left.

Wednesday’s campaign, however, is supported by 46 percent of the French, according to a recent survey by pollster Ipsos.

Unlike the Yellow Jackets, which began online in opposition to a fuel tax hike before entering the mainstream and bringing the country to a standstill, the “Block Everything” crusade’s goal is much more nebulous. Online accounts claiming to belong to the Sept. 10 movement are calling for a range of things, from an end to political parties to a boycott of the banking system and Macron’s resignation.

Nuñez said that the leaderless nature of the movement has fueled concerns about its unpredictability.

“It’s not like a demonstration, there are no organizers, no one we can talk to, just calls to block everything,” said Nuñez. “And more worryingly, the calls have been relayed by radical extreme-left [groups] who are calling for hardcore, sometimes violent acts.”

Authorities also fear that whatever happens on Wednesday will inflame protests next week, which are organized by French trade unions.