People need not have worried. Mr Trump told the thousands of people packed into the Walter Washington Convention Centre: "The Palestinians must come to the table knowing that the bond between the United States and Israel is absolutely unbreakable. They must come to the table willing to accept that Israel is a Jewish state and it will exist forever as a Jewish state."
By the time the candidate made that declaration he had the crowd eating out of the palm of his hand. Many, not all, in the hall gave him standing ovation after standing ovation.
Mr Trump presents a dilemma for the ultra-conservative faction in American Jewish politics which, in recent years, has come to dominate Aipac's thinking.
Leading commentators from this part of the community, such as William Kristol and Charles Krauthammer, have been harsh critics of the businessman.
Following the speech, Mr Krauthammer was grudgingly complimentary. He said that Mr Trump's talk had been about repositioning himself. "He said every cliché, every line, that has ever been invented to show one's support for Israel," the pundit told Fox News. "As a policy speech it's meaningless. He had to undo the damage of saying 'I'm neutral.'" Mr Krauthammer paid tribute to the candidate's speech-writers. "They know the Middle East. He didn't know Hizbollah from Hamas a few months ago." And, in what could be seen as a repositioning statement of his own, Mr Krauthammer said Mr Trump "looked presidential".
Despite the crowd's generally warm reaction to Mr Trump, the conference hosts were not entirely pleased. On Tuesday, Aipac president Lillian Pinkus read a statement to disavow Mr Trump's comment about Mr Obama. She said: "While we may have policy differences, we deeply respect the office of the president of the United States and our President, Barack Obama… There are people in our Aipac family who were deeply hurt last night."
Earlier in the day, Hillary Clinton, the Democratic front-runner, took a sideways shot at Mr Trump's comment on neutrality. "We need steady hands, not a president who says he's neutral on Monday, pro-Israel on Tuesday, and who-knows-what on Wednesday because everything's negotiable. Israel's security is not negotiable, and anybody who doesn't understand that has no business being our president."
Interestingly, the only Jewish candidate for president, and the only candidate who has lived on a kibbutz, Bernie Sanders, did not attend. He was in Utah at a long-scheduled campaign event. Mr Sanders had asked to address Aipac by video link, something prominent speakers have done in the past. For reasons that have not been explained, the organisation declined to allow this. Mr Sanders began his Utah talk by saying this was the speech he planned to give at Aipac, if the scheduling problem had been worked out.
"Peace will require the unconditional recognition by all people of Israel's right to exist. It will require an end to attacks of all kinds against Israel," Mr Sanders said. "Peace will require that organisations like Hamas and Hizbollah renounce their efforts to undermine the security of Israel. It will require the entire world to recognise Israel. Peace has to mean security for every Israeli from violence and terrorism." The Aipac crowd would have been delighted.
Mr Sanders added: "Peace also means security for every Palestinian. It means achieving self-determination, civil rights, and economic well-being for the Palestinian people."
It's not likely the 18,000 in attendance would have responded to that with a standing ovation.
