The majority of the lawmakers represent districts with substantive Jewish communities.
The question came in the middle of a longer phone conversation last year that was “mostly friendly and complimentary," according to Axios.
"I treasure my Israeli friends and family, Israeli food, books, art, cinema, and dance," Portman said.
Treasury Secretary Steve Mnuchin, who is Jewish, reportedly will lead the delegation of more than 250, according to an Israeli TV station.
The Alpha Epsilon Pi fraternity was suspended as police investigate allegations by two 19-year-old students who said they were sexually assaulted at two different parties at the fraternity house.