WASHINGTON — White House Chief of Staff Denis McDonough called for the end of Israel’s “50-year occupation” and doubled down on the Obama administration’s critique of Prime Minister Benjamin Netanyahu, in a warmly received speech to the lobbying group J Street in Washington Monday.

Speaking to the dovish group’s national conference, McDonough became the latest in a series of Washington officials to highlight the administration’s displeasure with Netanyahu, while also talking up the permanence of US-Israel ties, repeating Washington’s commitment to continued military, security and intelligence cooperation.

“No matter who leads Israel, America’s commitment to Israel’s security will never waiver,” McDonough said.

At the same time, McDonough said later, “an occupation that has lasted for 50 years must end,” referring to Israel’s 48-year hold on the West Bank.

The statement represented an unusually harsh repudiation of Israel’s control over the Palestinian territories, using a term the administration generally avoids.

The longtime confidant to US President Barack Obama said that the administration believes that “the best way to safeguard Israel’s long-term security is to bring about a comprehensive peace between Israelis and Palestinians.”

Washington, he said, “has long advocated direct negotiations” toward a two-state solution — a position, he noted, that Netanyahu embraced in his 2009 speech at Bar-Ilan University.

“That’s why the prime minister’s comments on the eve of the election, [which] made very clear that a Palestinian state will not be established while he is prime minister, were so very troubling,” McDonough said, referring to comments made by Netanyahu in a preelection interview with the NRG website in which he seemed to take a Palestinian state off the table.

McDonough rejected Netanyahu’s claims that he had not changed his position, as well as Netanyahu’s explanation that conditions in the Middle East must be more stable for a Palestinian state to be established.

“We cannot simply pretend that these comments were never made,” McDonough proclaimed, receiving a standing ovation from the 3,000-person audience.

McDonough did not, however, address the first precondition that Netanyahu stipulated earlier this week for Palestinian statehood — that the Palestinian Authority renounce its nearly year-old alliance with Hamas.

McDonough denied that the basis of the current low in US-Israel relations was based upon bad personal chemistry between Obama and Netanyahu.

“Nothing could be further from the truth,” he said, arguing instead that it stems from the fact that “America’s commitment to a two-state solution is fundamental to American foreign policy.

“We will look to the next Israeli government to match words with action and to policies that demonstrates a commitment to a two-state solution,” McDonough continued.

“In the end, we know what a peace agreement should look like. The borders of Israel and an independent Palestine should be based on the 1967 lines with mutually agreed swaps. Each state needs secure and recognized borders, and there must be robust provisions that safeguard Israel’s security.”

As the deadline for a political framework agreement with Iran approaches at the end of the month, McDonough said that “diplomatic engagement with Iran has already delivered concrete results. Through the Joint Plan of Action, we’ve succeeded in stopping the advance of Iran’s nuclear program and even rolling it back in key areas.”

He reiterated the terms for an agreement that the US National Security Advisor stated earlier this month during the American Israel Public Affairs Committee’s conference — that Iran would not be able to develop weapons-grade plutonium or to use its underground site at Fordow to enrich uranium; extend the amount of time it would take Iran to reach breakout capacity; and would establish “frequent and intrusive inspection” to prevent Iran from pursuing a nuclear weapon through a covert channel.

The White House chief of staff stressed that “the deal we are pursuing is both realistic and achievable. A scenario where Iran forgoes domestic enrichment capacity for all time would surely be ideal, but it’s not grounded in reality.”

“The bottom line is this: Compared to the alternatives, diplomacy offers the best and most effective way to prevent Iran from obtaining a nuclear weapon, and this is our best shot at diplomacy. We have to give diplomacy a chance to succeed,” McDonough added.

He had choice words for the 47 senators who, earlier this month, wrote a letter to Iran’s leaders warning that any deal signed without the consent of Congress was liable to be impermanent. “It was a blatant political move — as the president said, that is not how America does its business,” McDonough complained. “The letter was also critically flawed in its legal reasoning. We are pursuing a political arrangement with Iran that does not require congressional approval. Such deals are an essential, long-standing element of international diplomacy. Republican and Democratic presidents alike have relied on them.”

McDonough warned that legislation, such as the bill coauthored by Sen. Bob Corker (R-TN) and Robert Menendez (D-NJ) that would require Congress to vote on any deal, “would embolden hard-liners in Iran. It would separate the United States from our allies. And it would potentially fracture the international unity that has been essential to keeping the pressure on Iran.

“A good deal,” McDonuogh assured, “is the best way to reach our shared goal — preventing Iran from gaining a nuclear weapon.”

Acknowledging that “even if a nuclear deal is reached, our concerns about Iran’s behavior in the region and around the world will endure,” McDonough insisted that “to walk away from the opportunity to diplomatically and peacefully resolve one of the greatest threats to international security would not strengthen our hand to stop Iran’s destabilizing actions.”