Falling short of this narrow majority could force Netanyahu into a unity government with the rival Blue and White party, which opposes giving him immunity, and could even lead to his ouster. If formal charges are filed, he will face heavy pressure to step down.
Here are three factors that could determine the longtime leader's future: TURNOUT: Netanyahu has repeatedly accused his opponents of conspiring with Arab parties to "steal" the election and voiced unfounded allegations of widespread fraud in Arab districts.
These tactics, which have drawn accusations of racism and intimidation, were widely seen as suppressing Arab turnout in April's election. If Arab voters, who make up about 20% of the electorate, turn out in higher numbers this time, it could be bad news for Netanyahu.
Arab leaders have been working hard to rally turnout, while Netanyahu has tried to mobilize his own supporters with doomsday warnings of heavy Arab turnout. ON THE BUBBLE: Under Israel's system of proportional representation, parties must receive at least 3.25% of the vote in order to enter parliament.
Two small parties in the leftist opposition, Labor and the Democratic Union, have been polling near the minimum threshold, while a far-right ultranationalist party, Jewish Power, is also trying to squeak in.
If any of these parties fall short, their tens of thousands of votes would be wasted, complicating hopes of their larger allies to cobble together a coalition. FRENEMIES: In April's election, Netanyahu fell one seat short of securing a majority after his former protege, Avigdor Lieberman, refused to join his coalition. Netanyahu was then forced to dissolve parliament and trigger Tuesday's election.
Despite sharing Netanyahu's hard-line views toward the Palestinians, Lieberman objected to what he said was excessive influence by ultra-Orthodox religious parties. Lieberman's Yisrael Beitenu party is popular with fellow former immigrants from the former Soviet Union, who are overwhelmingly secular.
Opinion polls have shown Lieberman gaining popularity with the broader public after his refusal to back Netanyahu. If those polls stand up, Lieberman could emerge as the kingmaker, spelling trouble for Netanyahu.