The thundering ovations, slickly produced videos and legions of lawmakers were the same as ever. But something was missing as the American Israel Public Affairs Committee convened here this week for its annual conference: tension.

Vice President Joseph R. Biden Jr. and Prime Minister Benjamin Netanyahu of Israel, in back-to-back speeches on Monday, sought to smooth over any friction between the United States and Israel, three weeks before President Obama makes his first trip as president to Jerusalem.

“No president has done as much to physically secure the state of Israel as President Barack Obama,” Mr. Biden said to 13,000 cheering supporters of Aipac, the nation’s most influential pro-Israel lobbying group. Mr. Netanyahu, speaking via satellite from Israel, said he looked forward to thanking Mr. Obama when he travels there later in March.

The elaborate display of harmony was a departure from recent years, when the Aipac conference often showcased tensions between the Obama administration and Mr. Netanyahu over Jewish settlements in the West Bank or how best to curb Iran’s nuclear ambitions.

With the White House eager for a good-will visit, Mr. Netanyahu still struggling to form a new coalition government and the world’s major powers immersed in negotiations with Iran over its nuclear program, many of the usual ingredients for conflict are missing.

Mr. Biden took pains to emphasize Mr. Obama’s threat to use military force — if all else failed — to stop Iran from acquiring a nuclear weapon. “Presidents of the United States cannot and do not bluff, and President Barack Obama is not bluffing,” the vice president said, drawing one of several standing ovations for his remarks.

Mr. Netanyahu took a darker view, saying that “diplomacy has not worked” and that Iran was “running out the clock” in negotiations with major powers. He claimed that sanctions had not stopped Iran from continuing to enrich uranium as nuclear fuel. But he lavished praise on Mr. Obama for his pledge not to allow Iran to acquire a bomb.

During the president’s visit, Mr. Netanyahu said, he plans to raise threats from both Iran, which he said was moving closer to the “red line” with its nuclear program, and Syria. They will also discuss efforts to revive peace talks between Israel and the Palestinians, even if Mr. Netanyahu made clear that any deal could not compromise Israel’s security.

Among the participants, there was some quiet grumbling about why it had taken Mr. Obama so long to visit Israel, with some saying it undercut an otherwise strong record of support for an ally.

“Obama did not visit Israel his first term,” said Michael Weintraub, a retailer from Calabasas, Calif. “I think that was a mistake. I know how much the president is doing for Israel.”

Others expressed residual qualms about Mr. Obama’s choice of Chuck Hagel, the former senator, as defense secretary. Mr. Hagel had been fiercely criticized for comments he made about the influence of pro-Israel lobbying groups in Washington. Aipac, however, did not take a public position on Mr. Hagel’s candidacy.

After Mr. Biden’s speech, it issued a glowing statement, saying it welcomed “the vice president’s strong statement that the president is not bluffing in his commitment to prevent Iran from obtaining a nuclear weapon.”

In his last appearance before this group, soon after he took office in 2009, Mr. Biden warned, “You’re not going to like this,” before declaring that the Obama administration wanted Israel to stop constructing settlements, as a way to jump-start peace talks with the Palestinians.

This time, Mr. Biden did not mention settlements, and said little about the peace process, which has been paralyzed for most of Mr. Obama’s presidency despite his early efforts to play peacemaker. Administration officials have played down expectations that Mr. Obama will bring bold new proposals to revive the talks when he visits Jerusalem.

Instead, Mr. Biden focused his remarks on the threats to Israel, mainly from Iran. Mr. Biden cited what he said was the president’s unshakable commitment to Israel’s military superiority in the region: $3.1 billion in American military aid, some of which helped finance the construction of the successful antimissile system known as Iron Dome.

On Tuesday, Aipac’s supporters will fan out across Capitol Hill to lobby for continued American support. Although the across-the-board spending cuts forced by the so-called sequester will hit military spending hard, officials close to Aipac said that now was not the time to cut aid to Israel, given the multiplying threats in the Middle East.

Mr. Biden, in addition to reiterating Mr. Obama’s pledge not to allow Iran to obtain a nuclear weapon, said the United States would work with Israel to isolate Iranian-supported terrorist groups, like Hezbollah. “Hezbollah is a terrorist organization, period,” he said.

Both Mr. Biden and Mr. Netanyahu spoke about the need to prevent the chaos in Syria from putting that nation’s stockpile of chemical weapons at risk. Mr. Netanyahu said the weapons could fall into the hands of terrorist groups like Hezbollah.

“They’re like a pack of hyenas feeding off a carcass,” he said, “and the carcass isn’t even dead yet.”

The prime minister did not appear in person this year, as is his custom, because of the coalition negotiations. But he predicted that he would have a solid government in place by the time Mr. Obama arrived, and said he looked forward to showing him a “different Israel.”