WASHINGTON- Israeli Prime Minister Benjamin Netanyahu warned the United States on Monday that the nuclear deal it is negotiating with Iran could threaten Israel's survival and insisted he had a "moral obligation" to speak up about deep differences with President Barack Obama on the issue.

Even as he set the stage for a Washington visit that has strained U.S.-Israeli relations, Netanyahu sought to lower the temperature ahead of his controversial address to Congress on Tuesday, saying he meant no disrespect for Obama and appreciated U.S. military and diplomatic support for Israel.

The Israeli prime minister left little doubt, however, about his objections to ongoing talks between Iran and world powers, which he said would allow Tehran to become a nuclear-armed state.

"As prime minister of Israel, I have a moral obligation to speak up in the face of these dangers while there’s still time to avert them," Netanyahu told a cheering audience at the annual conference of the American Israel Public Affairs Committee (AIPAC), the largest U.S. pro-Israel lobby.

Netanyahu said the relationship between his country and the United States was "stronger than ever" and not in crisis.

The tense personal relationship between Obama and Netanyahu has sunk to a new low over the Israeli leader’s planned speech to Congress just weeks before an end-of-March deadline for a framework nuclear accord with Iran.

Netanyahu is expected to press U.S. lawmakers to block a deal with Iran that he contends would endanger Israel’s existence but which Obama’s aides believe could be a signature foreign policy achievement for the president.

The invitation to Netanyahu was orchestrated by Republican congressional leaders with the Israeli ambassador without advance word to the White House, a breach of protocol that infuriated the Obama administration and the president's fellow Democrats.

Obama has said he will not meet with Netanyahu during the visit, on the grounds that doing so only two weeks before Israeli elections could be seen as interference.

The partisan nature of this dispute has turned it into the worst rift in decades between the United States and Israel, which normally navigates carefully between Republicans and Democrats in Washington.

The high-profile visit has divided Israelis, driven a wedge between Jewish American groups and alienated many Democrats, including Jewish Democratic lawmakers.

Netanyahu's critics have said that scuttling the Iran negotiations could raise the risk of war in the Middle East. But asked about the possible impact of Netanyahu's speech to Congress, White House spokesman Josh Earnest said it was not expected to complicate Iran diplomacy.