WASHINGTON — In a rousing speech before Congress punctuated by more than 40 bursts of applause, Israeli Prime Minister Benjamin Netanyahu assailed the Obama administration’s nuclear negotiations with Iran, asserting bluntly that the United States was on the verge of making “a bad deal.”

Though he said he was “grateful” for all President Barack Obama has done for Israel, Netanyahu went on to excoriate the administration for failing to insist on terms tough enough or enduring enough to prevent Iran from acquiring a nuclear weapon.

“It doesn’t block Iran’s path to the bomb; it paves Iran’s path to the bomb,” Netanyahu said Tuesday.

The speech before a joint meeting of Congress gave the Israeli prime minister a rare platform for confronting a president with whom he has shared mostly animosity and for trying to stop or radically alter negotiations that are reaching a critical juncture. Obama has said that if Iran does not agree to the outline of an agreement by the end of March then further talks would be pointless.

Netanyahu made the most of the opportunity, invoking the Constitution, Moses and the Holocaust to argue that the United States and Israel should stand fast to block Iran from gaining weapons. He hailed Holocaust survivor and Nobel Peace Prize winner Elie Wiesel, who was in the gallery, and said “I wish I could promise you, Elie, that the lessons of history have been learned.”

WHITE HOUSE RESPONDS

Aware of the danger that Congress would be persuaded to try to scuttle a deal with Iran, the White House quickly responded to Netanyahu.

Speaking in the Oval Office alongside Defense Secretary Ashton Carter, Obama said that Netanyahu didn’t offer any “viable alternatives” to the nuclear negotiations with Iran. Obama, who had been on a conference call discussing Ukraine with European leaders during Netanyahu’s speech, said he read a transcript and that “there was nothing new” in it.

“We are pursuing a deal that verifiably prevents Iran from obtaining a nuclear weapon,” said a senior administration official. “Where is the better alternative? Simply demanding that Iran completely capitulate is not a plan, nor would any country support us in that position. The prime minister offered no concrete action plan.”

The official added that “the logic of the prime minister’s speech is regime change, not a nuclear speech.”

Netanyahu’s speech marked the climax of controversy that began six weeks ago when he accepted an invitation from House Speaker John Boehner, R-Ohio, to address Congress; Boehner sidestepped the usual protocol of consulting with the president and Democrats in Congress before issuing the invitation the day after Obama’s State of the Union address. Accusations that the plan was hatched to serve partisan purposes in the United States as well as in Israel, where voters will decide in two weeks whether Netanyahu remains in office, laid bare fissures between the prime minister and the Obama administration.

Netanyahu used the address on Tuesday to paint Iran as a sponsor of terrorism that is aggressively marching across the Middle East and determined to realize its nuclear ambitions. Netanyahu said the country poses a “grave threat” to Israel and the world.

“This is a bad deal. A very bad deal. We are better off without it,” he said. “Why should Iran’s radical regime change for the better when it can enjoy the best of both worlds? Aggression abroad, prosperity at home?”

Secretary of State John Kerry and Iranian Foreign Minister Mohammad Javad Zarif are talking in Geneva on Tuesday ahead of a March 24 deadline on the framework for a nuclear deal. But Netanyahu said that demands should be tougher and that “if Iran threatens to walk away from the table, call their bluff.” He said tough economic sanctions would bring them back to talks.

Leaks and a Reuters interview with Obama on Monday have provided some general outlines of the agreement being negotiated by the United States and five other world powers including Russia and China. As a condition for the talks, Iran agreed to eliminate its stockpile of highly enriched uranium needed for a nuclear weapon.

AN OUTLINE FOR A DEAL

The terms being negotiated would require inspections by the International Atomic Energy Agency, limits on the type and number of centrifuges that could be used for enrichment, full replies to IAEA questions about past activities including military activities, and continuing to turn uranium into rods used for civilian nuclear power or send the material to Russia. The goal is to establish at least one year of “breakout time” – the time Iran would need to develop a weapon if cooperation broke down.

Some of those terms are highly technical; new centrifuges would be four to five times more efficient than older ones Iran possesses. Energy Secretary Ernest Moniz, a physicist and former professor at the Massachusetts Institute of Technology, has joined the talks.

The United States initially asked Iran to agree to terms that would last 15 to 20 years, while Iran asked for a five- to 10-year period. Obama said Monday the duration would have to be “double digit.” After that period, say people familiar with the deal, Iran would still have to comply with IAEA guidelines and allow unfettered inspections by the agency. But limits on centrifuges could end.

“It’s not as though they are free to develop nuclear weapons,” said Robert Einhorn, an arms control export at the Brookings Institution who previously advised the State Department under President Obama. “There is still intrusive verification under additional protocols of the IAEA so we would be in a better position than today to detect movement toward nuclear weapons and there would still be the option of military action. It’s not as though it’s a free pass to nuclear weapons after expiration.”

But Netanyahu said a deal would only “whet Iran’s appetite” for more nuclear material. Playing off the title of an Ernest Hemingway novel, he said “this deal won’t be a farewell to arms. It would be a farewell to arms control.”

The prime minister also spoke of the Jewish holiday Purim, which begins Wednesday night. It celebrates the Jewish Book of Esther, where describes a plot by a high-ranking member of the Persian empire to kill the Jews; the plot is foiled by Queen Esther, who is Jewish.

“Today the Jewish people face another attempt by yet another Persian potentate to destroy us,” Netanyahu said.

He warned against viewing Shiite Iran as an ally against Sunni extremists in the Islamic State, declaring that “the enemy of your enemy is your enemy.”

IRANIAN THREATS AGAINST ISRAEL

He cited threats by Iranian leader Ayatollah Ali Khamenei to “annihilate” Israel and the implication of Iran – and its “tentacles of terror” – in various attacks around the world. He said nuclear talks should require a change in behavior. “If Iran wants to be treated like a normal country, let it act like a normal country,” he said.

Later in the Oval Office, Obama said he agrees with Netanyahu that Iran is a dangerous regime that has repeatedly threatened Israel and that “no one can dispute” that Iran has used anti-Semitic language against Israelis.

“But on the core issue, which is how do we prevent Iran from obtaining a nuclear weapon, which would make it far more dangerous and would give it scope for even greater action in the region, the prime minister didn’t offer any viable alternatives,” Obama added.

Nearly a quarter of congressional Democrats did not attend the speech, citing the politicization of the address and the disrespect they felt Netanyahu and Boehner had shown the president. Others attended reluctantly.

House Minority Leader Nancy Pelosi, D-Calif., who left the chamber as Netanyahu was saying goodbyes, said in a statement she was “saddened by the insult to the intelligence of the United States as part of the P5 +1 nations, and saddened by the condescension toward our knowledge of the threat posed by Iran and our broader commitment to preventing nuclear proliferation.”

Sen. Dianne Feinstein, D-Calif., told CNN that Netanyahu “clearly . . . doesn’t like what the deal is. What he didn’t say was what would happen if there was no deal” or what would happen if the United States’s negotiating partners – Britain, France, Germany, Russia and China – “all agreed, and the United States did not.”

Erel Margalit, a leading Labor Party candidate in the coming Israeli elections, was in the United States on Tuesday. “In three weeks, we’ll have a chance to set a new path for Israel,” he said. “Hopefully we can not just define ourselves by the threat we face but by the opportunities . . . with the United States as our main ally.”

He said the Labor Party shared Netanyahu’s concerns about Iran’s nuclear program, but he said “we want to work with the administration rather than have a showdown with it.”