Israel’s leaders are watching Iran’s upcoming presidential election with a mixture of resignation and dread, as top officials here say they have no reason to believe that a new government in Tehran will back away from a pursuit of nuclear weapons.

“I ask that nobody delude himself,” Prime Minister Benjamin Netanyahu told members of Israel’s parliament last week. “The results of the elections in Iran won’t change a thing.”

Warnings from Israel’s defense and intelligence establishment seem directed, in part, at the White House. Israeli officials have praised the United States for imposing tough economic sanctions on Iran, but they have also signaled concern that it has not produced a credible military threat that could thwart Iran’s nuclear ambitions.

Israel is urging the United States and Europe not to let their attention drift from a country it considers an existential threat.

Netanyahu said that although Iran has not crossed what he has called a “red line” — producing enough enriched uranium to enable it to quickly build a nuclear bomb — the Iranian program “is methodically moving forward.” Yuval Steinitz, minister for international affairs, strategy and intelligence, warned this week that he envisions Iran seeking to build not one or two nuclear weapons but “an arsenal of hundreds” of warheads.

The six candidates left in the race for Iran’s presidency hold varying views on economic and social issues, from moderate to conservative, but to Israel’s leadership, all answer to Iran’s supreme leader, Ayatollah Ali Khamenei.

All the candidates have pledged that Iran will continue to act on what they say is its right to develop a nuclear energy industry. Hours after a presidential debate concluded Saturday, Iran’s foreign minister, Ali Akbar Salehi, said his country’s nuclear policy will not change after the election, regardless of who wins. He stressed that the policy’s objectives are peaceful.

Speaking to foreign journalists on Monday, Steinitz said Iran has made the decision to pursue nuclear weapons.

“You don’t spend so much money and you don’t suffer $70 billion of losses in a year” because of international sanctions “only to show that you can spin some centrifuges,” he said, adding that a nuclear-armed Iran would change the course of history.

“Iran is different,” he said. “Never before has a religious fanatic government possessed nuclear weapons.”

Steinitz said that Iran is paying a heavy price to develop its nuclear abilities but that its leaders think it is worth the price.

“How can you convince them they are paying something for nothing?” Steinitz said. “Only with a crystal-clear military threat that, come what may, they won’t have the bomb.”

Asked who should make such a threat, Steinitz would not say, but his remarks made clear that he was talking about the United States.

“The indirect message to the United States is that this idea of waiting until after the election, to see what happens, has been a waste of time,” said Uzi Rabi, director of the Moshe Dayan Center for Middle Eastern and African Studies at Tel Aviv University.

Israel is “coming to the conclusion that the United States is not there,” Rabi said. “Not like it was in the Middle East before. And we’ll be left alone.”

He said Israeli concerns have only increased in recent weeks, as it appears that Syrian President Bashar al-Assad is gaining ground in the civil war in his country and that he has done so with help of his allies — Russia, the Lebanon-based militant organization Hezbollah and its sponsor Iran.

“We now have a linked crisis here, a new great game,” Rabi said. “Russia is pushing. The United States is hesitating. Israel is confused. And Iran is feeling stronger.”