JERUSALEM — The Israeli election on April 9 was supposed to be a referendum on Prime Minister Benjamin Netanyahu. Facing indictment on bribery charges and a stiff challenge from a career soldier who retired as the military’s chief of staff, Mr. Netanyahu, for the first time, was both deeply vulnerable and unable to persuade Israelis that he was clearly the best prepared to keep them safe.

Again and again this past week, Mr. Netanyahu appeared to lay bare those weaknesses. Yet suddenly it is the fitness of his opponent, Benny Gantz, that is being questioned.

Nothing played out as expected when Mr. Netanyahu flew to Washington on Sunday. It had promised to be a crowning moment, in which President Trump would proclaim United States recognition of Israel’s sovereignty over the Golan Heights, and Mr. Netanyahu would remind voters back home of his mastery of international diplomacy.

But a Gaza rocket strike north of Tel Aviv on Monday not only set off a new round of violence, it also reminded voters that Mr. Netanyahu’s policy in Gaza, such as it is, has been to count on the Iron Dome antimissile system, order largely symbolic retaliatory airstrikes that cause few casualties, hope for cooler heads to prevail, and then do little if anything until the next flare-up.