TEL AVIV — Israeli and American officials are saying that with elections fast approaching in both countries, completion of a nuclear deal with Tehran is unlikely before the end of baseball season — if at all — because any signs of appeasement toward Iran would weaken the political parties in power. 

Mossad’s chief, David Barnea, flew to Washington last week for meetings with American counterparts and was reportedly prevented from addressing Congress. In a rare public appearance today following his return to Israel, Mr. Barnea spelled out the dangers of a proposed agreement with Tehran, and made clear Israel will set its own course on Iran regardless of whether there is a deal. 

While at Washington, “I detailed to officials the ramifications of an agreement,” Mr. Barnea told an audience at Israel’s Reichman university. “Some $90 billion would flow into the Iranian coffers in the first year, and tens of billions in the years after that. No country has ever seen such immediate growth in its gross national product. What part of that windfall would be dedicated to terror?”

Iran’s moves to assassinate American officials and dissidents on American soil, the foiled bombing of an Iranian opposition group’s gathering near Paris, and a major recent cyber attack against Albania show that diplomacy “doesn’t restrain” Tehran, Mr. Barnea said. “It has the opposite effect. Terrorism on American and European soil only increases while the Vienna talks are ongoing.”  

Mr. Barnea argued that Iran would use its new cash inflow to beef up its presence in places like neighboring Lebanon and Syria. “Israel isn’t a party to this game,” he said, “We are familiar with the Iranian vision and we watch as it materializes. Even if there is an agreement, it would not immunize Iran from Mossad actions.”

Mr. Barnea may be the most hawkish opponent of an Iran deal among Israeli officials, but he is not alone. A Jerusalem consensus is emerging that current concession-laden American and European proposals to return to the 2015 Joint Comprehensive Plan of Action amount to, as Prime Minister Lapid put it recently, a “bad deal.” 

“Returning to the nuclear agreement under the current conditions would be a critical mistake,” Mr. Lapid said today during a Berlin visit. His German host, Chancellor Scholz, countered that a deal is the best way to stop Iran’s nuclear program, but that completing one is currently unlikely because of Iran’s negotiating tactics. 

Early on, Mr. Lapid bet on nonpublic dialog with Washington, aimed at impressing on the administration that Israel opposes the deal’s outlines. A host of Israeli officials have traveled to Washington recently, including the national security adviser, Eyal Hulata, and the defense minister, Benny Gantz, in addition to Mr. Barnea. They made no secret of their opposition to the recent America-backed European proposals at Vienna.

As Israel’s November 1 national election nears, a former premier, Benjamin Netanyahu, regularly taunts Mr. Lapid, saying that Washington is ignoring Jerusalem’s pleadings and that the prime minister’s “quiet diplomacy” is failing. The Biden administration, which barely hides its preferences in Israeli politics, would rather postpone a deal than help the much-despised Mr. Netanyahu. 

Then there are the November 8 midterm elections at home. As they near, Democrats seem to realize that an election-eve Iran deal, which they initially believed could put the power of their diplomatic skills on display, is far from a vote getter.

While in Israel last week, Senator Menendez, a Democrat, said that President Biden is committed to bringing any agreement he reaches with Iran for a congressional review — starting with a hearing at the Senate’s foreign relations committee that the New Jersey senator heads. 

Mr. Menendez said he doubted he could marshal 60 deal opponents in the Senate to override a presidential veto. Yet even a small Senate majority against the deal — as well as protracted televised hearings at Mr. Menendez’s committee — is unlikely to sway voters to back Democrats. 

“I don’t think there’s any chance the agreement will be announced before our election, or the Israeli election because the politics of this agreement are probably not good in either place,” Senator Graham, who accompanied Mr. Menendez on the Israeli trip, told Jewish Insider.

Yet, Mr. Graham added, despite fresh setbacks in the latest round of talks, “I’m assuming that” the Biden administration will eventually “get a deal, because they want a deal so badly.”

The politics in Iran may also prevent a quick completion of a deal: Tehran has long been iffy about returning to the JCPOA. As it tightens relations with Russia and China, and as American enforcement loosens, global sanctions are fast losing their bite. Additionally, Tehran hardliners who advocate “self-reliance” are gaining political power.

The country’s ailing supreme leader would rather drag out the negotiations than complete a deal, and he seems to enjoy humiliating European and American diplomats, exposing them as the deal-eager party. Unlike them, Israel refuses “to avert our eyes” and ignore Iran’s long term intentions, the Mossad’s Mr. Barnea said.