WASHINGTON — Senator Bob Corker of Tennessee was surrounded by a gaggle of constituents on Tuesday like a quarterback in a huddle, finishing a discourse on his commitment to stopping Iran from developing nuclear weapons.

Prime Minister Benjamin Netanyahu of Israel, center, met on Tuesday with Senators Harry Reid, left, and Mitch McConnell. Iran's nuclear program continues to dominate discussions.

Andrew Groveman, a real estate developer from Memphis, was leading the group of delegates from an Israel lobbying group, the American Israel Public Affairs Committee, through meetings on Capitol Hill. “As you know,” Mr. Groveman said, “we always have three points.”

“I thought this year the three were Iran, Iran, Iran,” said Mr. Corker, a Republican who sits on the banking committee that recently passed legislation tightening the noose of sanctions against Iran.

For three days, Iran has dominated the agenda of the annual conclave of Aipac, a must-have ticket for politicians eager to prove their pro-Israel bona fides.

In separate speeches to the record crowd of 13,000 people, President Obama, Prime Minister Benjamin Netanyahu of Israel and other leaders barely mentioned the words “Palestinian conflict,” and many in the audience said they had been moved to attend the conference because of what they see as the urgency of the Iran issue. If Iran developed nuclear weapons, many Aipac delegates agreed, it would pose an existential threat to the Jewish state.

“It’s a dangerous country,” was how 15-year-old Jonathan Turek of New Rochelle, N.Y., one of about 1,500 students at the conference, summed it up. “Dangerous man running the country.”

After two days of listening to politicians talk about the issue, Aipac members got a chance to talk back on Tuesday. Conference leaders scheduled a record 530 meetings with lawmakers over about four hours, with delegates from all 50 states fanning out across Washington bearing talking points.

(Which Congressional offices did not take meetings? Those of Representative Ron Paul, the Texas Republican campaigning for the presidential nomination; Representative Dennis J. Kucinich, an Ohio Democrat who has frequently voted against Aipac’s positions on Israel and Iran; Representative Donald M. Payne of New Jersey, who died Monday; the office vacated by Representative Gabrielle Giffords, the Arizona Democrat recovering from an assassination attempt; and a lawmaker Aipac officials would not name.)

In what might have been the largest blitz of citizen lobbying all year, lines of delegates at checkpoints at Congressional office buildings snaked outside, and about a third of the 100-member Tennessee group did not make it into the first session until a few minutes before Mr. Corker left.

This year, for the first time, a counterlobby was set up by Occupy Aipac, a group that also protested outside the conference and made several attempts to disrupt its sessions. Medea Benjamin, a co-founder of the peace group Codepink and an Occupy leader, said about 200 people divided into nine teams and met with Congressional staff members on Friday, Monday and Tuesday, bringing their own talking points.

“It is important for our congresspeople to hear from both sides,” said Ms. Benjamin, “and hear from Americans horrified about the possibility of a war with Iran.”

The Aipac crowd, though, wanted to make sure that members were taking the possibility seriously. After their session with Mr. Corker and his national security adviser, the Tennessee group met with Erin Reif, an aide to Senator Lamar Alexander, another Tennessee Republican. The aide said that she thought the new sanctions bill might pass as soon as this month — which some said is not soon enough.

“We want sanctions to work, but we wanted them to work a year ago,” one woman in the group told Ms. Reif. Invoking the speech to Aipac on Monday in which Senator Mitch McConnell of Kentucky, the Republican leader, promised to introduce a bill authorizing military force at the smallest hint of Iran moving to weaponize its uranium, the woman said Mr. Alexander should consider “not just an option, but every viable option.”

Then there were those other two points: Aipac members urged lawmakers to co-sponsor legislation to improve the security partnership between the United States and Israel, and to support the foreign-aid appropriation, which includes $3.1 billion for Israel.

Isaac Graber, a 15-year-old sophomore at Margolin Hebrew Academy in Memphis, presented the case for foreign aid, first to Ms. Reif and then again to Mr. Alexander, who arrived late. Isaac held a yellow legal pad but hardly referred to it, as he ticked off facts: foreign aid is about 1 percent of the federal budget; much of Israel’s $3.1 billion is spent on contracts with United States companies; Israel spends 8 percent of its gross domestic product on defense. “They’re such a tiny country surrounded by all these crazy neighbors,” Isaac said. “Really, the bottom line is this is a little bit of money that really goes a far way.”

Then he asked Ms. Reif if she had any questions.

“Do you want my job?” she said.