• Mr. Gantz, 59, is a three-star general who fought two wars in Gaza, giving him credentials to challenge Mr. Netanyahu’s “Mr. Security” persona. In campaign ads, Mr. Gantz both boasted about “terrorists killed” over his military career and suggested he could be a peacemaker. He teamed up with two other former army chiefs and another centrist, Yair Lapid, to try to court voters in the middle of the ideological spectrum.

Kingmakers and a political brawl

• Under Israel’s chaotic and confusing parliamentary system, a panoply of small parties could tip the balance of power. The unlikeliest kingmaker is an iconoclastic politician, Moshe Feiglin, last seen pushing a far-right agenda of annexing the entire West Bank. He is now calling for the legalization of marijuana and has put out proposals aimed at reducing the cost of living: a flat tax, privatization of hospitals, an end to import tariffs, and land reform to lower housing costs.

• The Arab vote is also a wild card — especially as, on the eve of the election, Mr. Netanyahu pledged to begin annexing parts of the West Bank, a potentially fatal blow to the prospects for a peace agreement with Palestinians. A strong turnout among Palestinian citizens of Israel, who make up 20 percent of the population, could raise the number of votes needed to make it into Parliament, jeopardizing smaller parties on the right and the left. Yet Arab voters have seemed even less enthusiastic about voting than Jews, and a boycott-the-vote campaign has gained strength in the past month.

• Whoever wins in the electoral contest will have to cobble together a coalition in Parliament, where no party has ever won a 61-seat majority outright. Here’s our guide to the factions and system.