WASHINGTON - The formidable political strength of the American Israel Public Affairs Committee, the nation's major pro-Israel lobby, has been on decidedly intentional display here in the last few days.
But this year, Aipac's annual conference comes after a period fraught with small anxieties for the group and its supporters.
Just days ago, the Obama administration said it was seeking the dismissal of charges that two former Aipac analysts had violated an espionage statute by improperly disseminating national security information.
The case against Steven J. Rosen and Keith Weissman had raised what many in the pro-Israel community in the United States regard as an unfair, even toxic question about whether the loyalty of some American Jews to Israel matches or exceeds their loyalty to the United States.
Gary Silow, a Philadelphia-area lawyer and Aipac member at the convention, said he was deeply troubled by the potential for renewed discussion of what he said was the offensive "dual loyalty" issue. In Mr. Silow's view, "the fact that they came after Aipac was what was really disturbing."
Like many at the convention, Mr. Silow said he was relieved at the move for a dismissal.
More than half the members of the House and Senate attended Monday night's dinner, which featured the group's "roll call" in which the lawmakers all rise. It is a conscious - and effective - effort to demonstrate the group's influence on Capitol Hill.
Even as the charges were dismissed, the issue of Aipac's role in the capital's political life surfaced again in recent days with the disclosure that Representative Jane Harman, Democrat of California, had been overheard in 2005 on a government wiretap offering to help reduce the charges. Ms. Harman, who has denied she intervened in the Rosen-Weissman case, was greeted with sustained applause when she appeared on Sunday morning.
The site of the conference, the Washington Convention Center, is conveniently, and symbolically, about equally close to the White House and the Capitol, the two objects of Aipac's muscular demonstration. Along with 6,000 delegates, mostly Jewish, leaders of the two branches of government have been attending the convention to offer praise for Aipac and support of Israel, both in generally unreserved language.
The roster of scheduled guests from Sunday through the meeting's conclusion on Tuesday included Vice President Joseph R. Biden Jr.; Senator John Kerry, the Massachusetts Democrat who is chairman of the Foreign Relations Committee; Newt Gingrich, a former House speaker who remains an important Republican voice; and Rahm Emanuel, the White House chief of staff, who has longstanding ties to Israel. The group also heard from the new Israeli prime minister, Benjamin Netanyahu (via satellite), and the new opposition leader, Tzipi Livni, and the president, Shimon Peres (in person).
Huge slides of former American presidents were displayed, and there was a murmur of disapproval when the image of Jimmy Carter appeared. Mr. Carter brokered the Camp David peace accords but has turned harshly critical of Israel since leaving office.
Speeches are scrutinized closely at Aipac events. As a presidential candidate in June 2008, Barack Obama spoke to Aipac to counter whispers in the American Jewish community that he was insufficiently committed to Israel. Mr. Obama told the group that he regarded them as "friends who share my strong commitment to make sure that the bond between the United States and Israel is unbreakable today, tomorrow and forever."
Mr. Obama went on to win an estimated 78 percent of the Jewish vote, a figure higher than that won four years earlier by Mr. Kerry.
Many of the Aipac attendees are planning to fan out on Capitol Hill on Tuesday to brace lawmakers with their views. Aipac's spokesman, Josh Block, said there were 508 appointments at Congressional offices.
The conference's literature is filled with suggestions for lobbying as in "don't be late" and "be direct" in making your case.
Aipac officials say the key to their success is linking their supporters across the country with their local elected lawmakers. "Relationships matter" is a slogan plastered around the convention hall. Aipac does not make political donations but encourages its members to do so.
Last year, some prominent American Jews, asserting that Aipac's generally down-the-line support of Israeli policy was neither helpful to Israel nor wise, founded a counter group called J Street. J Street, which is only a tiny percentage of the size of Aipac, is vocal about supporting lawmakers who might disagree with some Israeli policies. Aipac officials have tried to treat J Street as if it were lint.