ROME — Italy’s golden period of stability suddenly seemed on the familiar precipice of chaos on Thursday after Prime Minister Mario Draghi tendered his resignation in response to a revolt by anti-establishment populists within his broad national unity government.

But in a sign of how traumatic Mr. Draghi’s departure would be for Italy, the country’s president refused to accept his resignation, essentially freezing the political situation in place until next week, when Mr. Draghi will address Parliament.

The unexpected government crisis, and the theatrics and behind-the-scenes machinations, left Italy in a state of suspended animation and created a potential calamity for Europe as it seeks a united front against Russia’s aggression in Ukraine, and faces a wave of Covid infections and an energy crisis.

On Thursday night, Italy’s politicians and analysts struggled to figure out exactly what had happened — and what would happen next. Despite Mr. Draghi’s stated intention to resign, it remained possible that he could remain in power if key political players rejected the temptation to bolt and fall back in line.

Among them is the man who triggered the revolt, former Prime Minister Giuseppe Conte of the Five Star Movement.

But the day’s events also made clear that the gravity of scheduled elections in early 2023 would continue to pull all the parties apart, and that Mr. Draghi, who had made government unity a condition of his staying on, may yet insist on quitting.

In tendering his resignation, Mr. Draghi had said that “the majority of national unity, which supported this government since its inception, no longer exists.”

Italy’s president, Sergio Mattarella, “did not accept the resignation,” according to a statement from Mr. Mattarella’s office, and instead invited Mr. Draghi to speak to Parliament in the coming days to address “the situation that has arisen.”

Most agreed that the next five days, ahead of Mr. Draghi’s speech in Parliament to explain his reasoning, would be crucial.

“There are five more days to work so that Parliament can confirm its confidence to the Draghi government and Italy can exit the dramatic tailspin it is entering right now,” Enrico Letta, the leader of the Democratic Party, said in a Twitter post.

If Mr. Mattarella or the political parties that would like the government to continue cannot convince Mr. Draghi to stay, it would mean instability not just for Italy but for all of Europe, and at a precarious time. The European Union, of which Mr. Draghi is a fervent advocate, is struggling to keep unity in the face of the aggression in Ukraine by President Vladimir V. Putin of Russia.

After Mr. Draghi took office in early 2021, when Italy’s president asked him to resolve a political crisis created by the collapse of Mr. Conte’s government, he led the country out of the worst days of the Covid pandemic and packed the government with highly accomplished experts who shook Italy out of its political and economic malaise.

Mr. Draghi, a titan of Europe often called Super Mario for his role in saving the euro as president of the European Central Bank, immediately boosted Italy’s international standing and investor confidence.

The promise of his steady hand at the wheel helped Italy receive more than 200 billion euros, or about $240 billion, in relief funds from Europe — a transformational sum that gave Italy its best chance at modernization in decades.

Mr. Draghi brought moderate growth to Italy, made reforms to its justice system and tax code, streamlined Italy’s bureaucracy, and found diverse sources of energy away from Russia, including renewables.

Along the way, he made populism unfashionable and competence admirable, and he repositioned Italy as a reliable force for democratic values within Europe.

Perhaps most crucially, he played a significant role in pushing Italy, which has often maintained a close, transactional and ambiguous relationship with Russia, into the European mainstream on questions of support for Ukraine and sanctions against Russia. Italy was the first major Western nation to publicly support Ukraine’s eventual membership in the European Union.

The potential departure of Mr. Draghi opens the door to forces who are much more sympathetic to Mr. Putin.

Matteo Salvini, the nationalist leader of the League party who once wore shirts with Mr. Putin’s face on them, and whose popular support and institutional influence has waned over the last two years, suddenly mattered again.

While Five Star, after triggering the crisis, seemed willing to perhaps support the government after all, Mr. Salvini, who has also made enormous demands on Mr. Draghi, now had reason to declare the government over, allowing him to return, without necessarily accepting the blame, to the campaign footing he excels on.

“If a coalition party doesn’t back a government decree that’s it, enough is enough,” Mr. Salvini said on Italian television. “It seems clear that we should go to elections.”

He is not the only Italian political force that would welcome Mr. Draghi’s departure and the ushering in of early elections.

“With Draghi’s resignation, for Brothers of Italy, this legislature is over,” said Giorgia Meloni, the hard-right leader who has stayed in the opposition and seen her popularity skyrocket over the last year and a half. “This Parliament no longer represents Italians. We will fight to return to the Italian people what the citizens of all other democracies have: the freedom to choose who represents them. Elections immediately.”

The revolt by what remained of the once powerful and anti-establishment Five Star Movement was led by Mr. Conte, who has made a habit of demanding concessions from Mr. Draghi for his continued support.

He has argued that the government has not set aside enough funds for a cost of living package. Five Star — which is traditionally close to Russia — has also opposed sending significant military support to Ukraine in response to the Russian invasion.

This time it was over a relief bill for soaring energy costs that included a garbage incinerator in Rome that Five Star found unacceptable.

Mr. Draghi, after days of seeking a compromise with Mr. Conte, opted for a confidence vote early Thursday in an effort to call Mr. Conte’s bluff. This time Mr. Conte led his party in a walkout.

Though the government survived — by a vote of 172 to 39 — Mr. Draghi had made clear that he would not lead a unity government that had no unity. Convinced that the coalition was no longer tenable, he decided the time had come for him to leave as well.

“In the past few days, on my part I put the utmost effort to continue on the common path, even trying to meet the needs that had been advanced by the political parties,” Mr. Draghi said in his announcement of resignation, adding that unity was “fundamental in tackling the challenges of the past few months. These conditions are no longer there. I thank you for your work, the many results achieved.”

Five Star, whose support crumbled after a chaotic spell running the government and Mr. Draghi’s succession, would most likely suffer terribly if Italy held new elections. But as the 2023 deadline for elections draws nearer, Five Star also has less to lose, and Mr. Draghi’s government was expected to face more internecine fighting and instability in any case.

It arrived sooner than expected, though it was not entirely surprising that the threat came from Mr. Conte.

Mr. Conte, a lawyer plucked from obscurity by Five Star and the League to lead the government in 2018, has struggled to find his footing as a political leader of what is left of Five Star.

He is still bitter, members of Parliament say, over being pushed out as prime minister in 2021, when he was replaced by Mr. Draghi, and he is desperate to rebuild a party that has wasted away, hemorrhaging half of its support.

The Five Star leader who brought him in as prime minister — Luigi Di Maio, the current foreign minister — quit the party last month, taking dozens of members with him. Mr. Di Maio, a onetime firebrand, now follows in Mr. Draghi’s footsteps and speaks about the importance of NATO, clearly seeing his future in the establishment.

Mr. Conte has struggled to signal to his unsatisfied supporters that he can deliver on their interests. He speaks in legalistic terms, is often inconsistent and has the added headache of constantly trying to appease the party’s often inscrutable founder, Beppe Grillo.

“The scenario has changed,” Mr. Conte told reporters after failing to reach a compromise during talks with Mr. Draghi on Wednesday. “We need a different phase.”

Gaia Pianigiani contributed reporting from Siena, Italy.