JERUSALEM — Heading into the third Israeli election in a year, the candidates got desperate. And things got ugly.

In a deadlocked race ahead of Monday’s vote, Benny Gantz, the former Israeli Army chief, is trying to unseat Benjamin Netanyahu, the longtime prime minister, whose criminal trial on bribery and other corruption charges is to begin on March 17. The first two votes, in April and September, were inconclusive: Neither man was able to form a governing majority.

Each passing day brought another sordid bombshell.

Mr. Gantz’s top strategist called his client a coward in a private conversation with his rabbi. The rabbi was secretly taping him; a day after the rabbi met with Mr. Netanyahu, the recording aired on the nightly news.

Mr. Netanyahu’s wayward son, Yair, gleefully spread unsubstantiated rumors online that Iran had obtained material with which to blackmail Mr. Gantz, including a purportedly intimate video from his cellphone. Mr. Gantz vehemently denied it.