The group’s Democratic counterpart, the Jewish Democratic Council of America, took a harder line, calling on Mr. Santos “to not take the oath of office” in a post on Twitter and challenging the R.J.C.’s integrity for not doing the same.
The R.J.C. has taken a tougher stance on perceived affronts to the Jewish community before.
It repeatedly demanded that Congress remove Representative Ilhan Omar, Democrat of Minnesota, from her seat on the House Foreign Affairs Committee for remarks about Israel and Israeli politics that the group termed “antisemitic tropes.”
The coalition also condemned Representative Marjorie Taylor Greene of Georgia in 2021 for making antisemitic comments on social media, and called her out a second time — along with Representative Paul Gosar of Arizona — for speaking at a white nationalist conference.
Gabriel Groisman, the former mayor of Bal Harbour, Fla., and a member of the coalition’s board of directors, said he had met Mr. Santos at the Las Vegas event and had been excited that a Jewish Republican was elected to the New York delegation in Congress, but called the recent revelations “extremely offensive.”
He went beyond the R.J.C. statement, saying that “the Republican leadership should condemn Santos publicly, and he should not be given any committee assignments.”
“Thankfully, terms in Congress are only two years,” Mr. Groisman added. “Hopefully we can get him out as soon as possible.”
But one of the group’s new board members, Josh Katzen, the president of a Massachusetts commercial real estate firm, pointed to multiple examples of Democrats who were accused of embellishing their records in the past, including Hillary Clinton, who claimed in 2008 that she had to run across a tarmac to avoid sniper fire during a 1996 trip in Bosnia, and President Biden, who said he finished in the top half of his law school class and attended on a full academic scholarship.