Israelis vote Tuesday in their fourth parliamentary election in just two years. Once again, the race boils down to a referendum on Prime Minister Benjamin Netanyahu.

Netanyahu, who has served as prime minister for the past 12 years, hopes voters will reward him for leading the country’s successful coronavirus vaccine rollout and his diplomatic outreach to the Arab world. His challengers have highlighted his earlier missteps in the coronavirus strategy, his reliance on divisive religious and ultra-nationalist allies and his ongoing corruption trial.

Over the years, Netanyahu has developed a reputation as a political magician and master manipulator capable of surviving any crisis. With witnesses set to take the stand against him next month, Netanyahu is hoping for another miracle that could deliver a friendlier parliament willing to grant him immunity or freeze his trial.

Opponents portray him as a serial liar who has caused two years of political paralysis by putting his political survival and legal troubles ahead of the country's interests.

Opinion polls forecast an extremely tight race, raising the possibility of continued deadlock and even an unprecedented fifth consecutive election.

Netanyahu appears to hold a slight advantage because of the intricacies of Israel’s political system.

In Israel, people vote for parties, not individual candidates. Netanyahu’s Likud is again poised to emerge as the largest individual party. But since no party has ever won a 61-seat parliamentary majority on its own, political alliances must be formed to create a governing coalition.

If the opinion polls prove accurate, Netanyahu would have a clearer path to building a government than the array of rivals that have little in common beyond their animosity toward him. Here is a look at the key factors that could determine whether Netanyahu or any of his challengers can clinch that elusive 61-seat majority.

Vaccination

Netanyahu has staked his reelection hopes on the success of Israel’s successful vaccination campaign. Netanyahu last December moved quickly and aggressively, personally lobbying the CEOs of Pfizer and Moderna to secure enough vaccines for Israel’s 9.3 million people. In under three months, Israel has vaccinated some 80% of its adult population. With infection rates plunging, that has allowed the country to reopen schools, restaurants, museums and the main airport just in time for election day.

Opponents have accused Netanyahu of bungling the management of the pandemic over the past year. A series of lockdowns hit the economy hard, thousands of businesses failed and unemployment remains in double digits. Many also have bitter memories of Netanyahu’s ultra-Orthodox allies flouting lockdown rules and point to the country’s more than 6,000 COVID-19 deaths.

With the economy coming back to life, Netanyahu is hoping the growing sense of normalcy will make voters forget the difficulties of the past year. This may explain that while polls show a majority of Israelis want Netanyahu replaced, he also is seen as best-suited to be prime minister.

"In people's minds, first and foremost when you go into an election, is the identity of the prime minister," said Yohanan Plesner, president of the Israel Democracy Institute. "In many ways, this works in Netanyahu's favor because it's unclear who the opponent is."

Should I stay or go?

Opinion polls have indicated that some 15% of voters remain undecided. Tuesday's election will hinge not only on who these voters support but whether they choose to vote at all. Analysts expect turnout to be lower than the 71% level of the most recent election a year ago, in part because of continued concerns about the coronavirus along with general voter fatigue.

Israel is providing special accommodations, including separate booths and mobile ballot stations, to allow people who are sick or in quarantine to vote. But more important than overall turnout will be voter participation in key sectors.

Netanyahu’s religious and nationalist allies tend to have highly motivated voters. On the other hand, Arab voters, disappointed with the disintegration of the umbrella "Joint List" party, are expected to stay home in larger numbers this time around. Voters in the more liberal and secular areas around Tel Aviv also tend to have lower rates of participation. Netanyahu could benefit if these trends materialize.

On the edges

This election could well hinge on the showing of a few small parties. In order to enter the Knesset, or parliament, a party must receive at least 3.25% of the vote, giving them a minimum of four seats in the 120-seat body.

Pollster Camil Fuchs said four small parties are hovering near the threshold. Of these, the dovish Meretz party and the centrist Blue and White are "much more in danger" of not getting enough support, according to recent polls, he said. Both are members of the anti-Netanyahu bloc.

The Religious Zionist party, a small pro-Netanyahu faction that includes openly racist and homophobic candidates, appears to be gaining strength. If one of the anti-Netanyahu parties fails to get in, a strong showing by the Religious Zionists could help put Netanyahu over the edge.

The kingmakers

Despite the tight race, neither Netanyahu and his religious and hardline allies, nor the anti-Netanyahu bloc, led by centrist Yair Lapid’s Yesh Atid party, are expected to capture a majority of seats on their own. That sets the stage for former Netanyahu aide Naftali Bennett to emerge as the decisive voice in coalition building.

Bennett’s Yemina party supports the same hardline ideology as the Likud. But the two men have a notoriously strained relationship, and Bennett has refused to commit to either side. Given their similar world views, Bennett, who has served as Netanyahu's education and defense minister, appears to be better suited to join Netanyahu than the anti-Netanyahu bloc, which ranges from dovish Arab parties to hard-line former Netanyahu allies who have had bitter personal breakups with him. Still, if offered the chance to be prime minister, Bennett could side with Netanyahu’s opponents.

Some polls have forecast both sides falling short of a coalition even with Bennett’s support. That could create the unlikely scenario of a small party led by Arab lawmaker Mansour Abbas as kingmaker – or simply forcing the fifth election.

Missing in action

In the previous three elections, Netanyahu boasted of his close alliance with then-President Donald Trump, posting massive billboards on highways and high-rises showing the men together. With Joe Biden now occupying the White House, Netanyahu has barely mentioned the new president, whose administration has given him a cool reception.

Likewise, there has been almost no mention of the Palestinians, reflecting the yearslong freeze in substantive peace efforts. But Biden has indicated he will soon reengage with the Palestinians. That could make it difficult for the next Israeli leader to ignore the issue – or Biden.