This is an interesting question and I didn’t have an immediate answer. Let me start off by pointing out that many many Jews in the US are horrified at the genocide in Gaza and do not want to be associated with AIPAC at all. The Jewish community in the US seems to be engaging in very serious internal debate on the topic (https://mondoweiss.net/2017/03/daughter-defense-apartheid/).
AIPAC itself doesn’t seem to have any direct statements about Mandami at all. They do make the dubious claim that there “are more than 6 million pro-Israel Americans” (https://www.aipac.org/). Since there are an estimated 7.1 to 7.7 million Jews in the US (https://en.wikipedia.org/wiki/American_Jews) they claim to represent the vast majority of Jews in the US.
I’m guessing that OP is referring to a sermon by Rabbi Elliot Cosgrove (https://pasyn.org/sermons/2025/on-the-record/). I can’t find any statements on if he is or is not an official member of AIPAC but he is generally described as a very conservative by various Jewish publications. Jonathan Shulman then encouraged rabbis across the country to sign the letter. (https://www.jpost.com/diaspora/article-873068). He left AIPAC after 18 years because “the group’s brand was becoming increasingly toxic amid the war in Gaza.” As of Friday, over 1,000 rabbis have signed (https://jewishmajority.org/a-rabbinic-call-to-action).
My read on this is that AIPAC is now known to be bad marketing and it’s already getting rebranded; the people behind it will just regroup under a new name. While they didn’t claim responsibility for the letter, their supporters created and spread it.
edit: typos
Scale matters.
Squid guy’s atrocities were always limited to what he could do with a Kraken and a single ship.
EIC turned exploitation into an organized system that empowered hundreds of vessels and spread the suffering to entire continents.
edit: grammar