PARIS—French democracy wasn’t built for the crisis that’s enveloping the presidency of Emmanuel Macron .

In an effort to pull France out of its fiscal spiral, Macron is exhausting a battery of tools available to him under the constitution as guarantor of France’s modern Fifth Republic. He dissolved a rowdy National Assembly last year only to see voters elect an even more divided lower house of parliament. Since then, he has appointed one prime minister after another, only to see them felled in confidence votes or resign.

As Macron runs out of options, the president is becoming increasingly isolated. His own allies have begun to question whether he is pushing the architecture of French democracy to a breaking point.

“This crisis is the collapse of the state. That’s what I believe,” said Édouard Philippe , a center-right politician who served as Macron’s first prime minister.

The sense that France is caught in a doom loop was underscored Monday when Sébastien Lecornu—Macron’s fourth prime minister in just over a year— resigned from his post . He quit a mere month into the job after struggling to form a cabinet and unite lawmakers in the National Assembly around a budget that narrows France’s yawning deficit.

On Tuesday, Philippe added his voice to a chorus of political leaders who say Macron needs to step back from the fray and leave office before his term ends in 2027. Philippe, who plans to run for president, said Macron should appoint a new prime minister to urgently pass a budget and shortly thereafter organize early presidential elections.

Macron has refused to step aside. Instead, he is wielding the unspoken threat of dissolving parliament and calling snap parliamentary elections—yet again—to coerce lawmakers that he believes are largely reluctant to face voters. He instructed Lecornu, his defunct prime minister, to hold talks with political parties until Wednesday evening in a last-ditch attempt to steer the National Assembly toward a deal that can rein in the country’s budget deficit, which stood at 5.8% last year.

“A dissolution will not solve the problem,” said Olivier Costa, a research professor at the Paris-based Sciences Po university and France’s National Center for Scientific Research. “The problem will remain the same: how to govern the country without a majority,” he added.

Part of the problem is that Macron is using the powers of his office in a manner that is out of step with the political realities of the 21st century.

General Charles de Gaulle, the World War II hero and architect of the Fifth Republic, designed the presidency to govern with the backing of a majority in the National Assembly. If the National Assembly fell out of line, a president could call snap elections and expect a new majority to emerge from one of the two establishment parties—the conservatives and the socialists—that traditionally dominated at the polls.

Macron is operating in a very different political landscape. Antiestablishment sentiment across the West has fueled the rise of populist parties , including Marine Le Pen’s far-right National Rally and the far-left party of Jean-Luc Mélenchon . So when Macron dissolved the National Assembly in the summer of 2024, voters responded by electing the most fractious parliament in the Fifth Republic’s history.

Le Pen’s party garnered more seats than any other, but not enough for a majority, while Macron and his allies saw their ranks shrink to a mere 161 votes in the 577-seat lower house. The remaining seats went to establishment conservatives and an array of leftist parties that include Mélenchon’s forces.

“There is no democratic constitutional system that allows you to maintain political stability with only a third of the National Assembly behind you,” said Benjamin Morel, a professor of public law at Paris-Panthéon-Assas University.

The only thing that now unites left and right in the National Assembly is their willingness to buck Macron’s authority. The assembly has ousted two of Macron’s prime ministers in less than a year after each sought to trim billions in public spending in a bid to shrink a budget deficit that has ballooned under Macron ’s leadership. The turmoil has driven up France’s borrowing costs to levels rivaling the eurozone’s debt-laden periphery.

The yield on France’s 10-year bonds stood at 3.6% on Tuesday, above Greece’s, and neck-and-neck with Italy’s.

Even lawmakers within Macron’s own party are chafing over his attempts to micromanage the assembly. Gabriel Attal, who leads Macron’s centrist party, faulted the president for appointing politically skewed prime ministers to lead budget negotiations rather than allowing political parties to reach an agreement beforehand. The method, he said, reflected Macron’s failure to accept that power has shifted to parliament.

“I don’t understand the decisions of the president anymore. There was the dissolution and since then there’s been decisions that suggest a relentless desire to stay in control,” Attal said.

With his allies turning their back, Macron is looking more solitary than ever. Shortly after his latest prime minister resigned on Monday, Macron was seen walking by the River Seine in crisp fall temperatures. Bodyguards walked ahead and behind, keeping their distance.

Write to Noemie Bisserbe at noemie.bisserbe@wsj.com and Stacy Meichtry at Stacy.Meichtry@wsj.com