TEL AVIV—Israeli Prime Minister Benjamin Netanyahu’s coalition partners withdrew their support for the government, raising the possibility that it could collapse and send the country to a fourth election in less than two years.

A preliminary reading of a bill introduced by the opposition to dissolve parliament passed 61-54 on Wednesday, with Mr. Netanyahu’s coalition partners, the centrist Blue and White party, voting in favor of it. It will need to pass three more votes to become law, a process that will likely stretch into next week or longer. The parties could still reach a compromise that could avert the government’s collapse.

The dissolution of the Knesset, Israel’s parliament, would trigger a fresh election, likely in March.

The prospect of that underscores the continuous pressure Mr. Netanyahu faces amid what may be his toughest political challenges to date: managing the coronavirus pandemic, along with its economic fallout, while standing trial for corruption.

After three elections in the space of one year, Mr. Netanyahu failed to cobble together enough support and in May joined a unity government with Blue and White leader Benny Gantz. Ahead of Wednesday’s vote, Mr. Gantz said his party would support the measure introduced by Yesh Atid leader Yair Lapid, who split from Mr. Gantz’s party when the latter joined Mr. Netanyahu’s government.

“Netanyahu is on a path of personal survival,” Mr. Gantz said Tuesday in a speech, adding that Mr. Netanyahu lied to him and the country when forging a coalition agreement in the spring. “The only index for his decision making is relevance to his ability to evade trial, which is just around the corner.”

If their agreement proceeds as planned, Mr. Gantz is set to take over as prime minister in November 2021.

Analysts and lawmakers have long suggested that Mr. Netanyahu would look to hold elections before ceding his leadership post to a political rival. So long as he is prime minister while his corruption trial is under way, he could receive more favorable treatment from the legal system and gain support for immunity from the charges he faces. Witness testimony begins early next year.

Lawmakers in Mr. Netanyahu’s party have said he plans to allow the rotation government to proceed. But some of the prime minister’s allies have given radio interviews in recent weeks saying Mr. Gantz isn’t fit to lead the country because of what they say are his violations of the coalition agreement.

Political opponents and some analysts say the prime minister is once again looking to form a majority government where he could find support for immunity legislation. He denies wrongdoing and says the corruption probes are aimed at forcing him from power. But a return to the ballot box also presents a risk for the country’s longest-serving leader because some recent polls show that a center-right coalition without Mr. Netanyahu could gain enough support in the next vote to form a government without him.

Mr. Netanyahu voted against dissolving the Knesset.

Israeli Defense Minister Benny Gantz supported a bill introduced to dissolve parliament.

Israeli Defense Minister Benny Gantz supported a bill introduced to dissolve parliament.

Photo: Alex Kolomoisky/Press Pool

“This is not the time for elections—it’s the time for unity. This is the time to bring vaccines. This is a time to continue our determined war against the coronavirus,” he said in a video statement Tuesday.

Mr. Netanyahu might try to forge a compromise with Mr. Gantz on the budget and prevent parliament from dissolving.

The budget has become a flashpoint because the coalition agreement’s rotation clause only takes effect if it is passed. Parliament will automatically dissolve if the government doesn’t pass a budget by midnight on Dec. 23. The finance ministry, which forms the budget and has seen a number of senior officials quit recently citing mismanagement, is controlled by a minister from Mr. Netanyahu’s Likud party.

In recent weeks, the relationship between Likud and Blue and White has deteriorated to the point that the government no longer holds regular meetings unless they are about the coronavirus, government officials say.

Former Defense Minister Naftali Bennett, whose right-wing Yamina party is polling close to Mr. Netanyahu’s Likud, voted to dissolve parliament over the government’s handling of the coronavirus crisis.

“Today either the government falls apart, or the state of Israel falls apart,” Mr. Bennett said Wednesday.

Mr. Bennett’s popularity has soared in opinion polls in recent months after he helped lead Israel’s initial response to the coronavirus as defense minister, and has remained a public voice on the issue. Some polls suggest he could be best positioned to form a coalition without Mr. Netanyahu after a March ballot.

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Write to Felicia Schwartz at Felicia.Schwartz@wsj.com