This is not the first time the roiling debate on college campuses over divestment from Israel has led to charges of anti-Semitism. Earlier this year, students at the University of California, Los Angeles, asked a Jewish student who was a candidate for a campus judicial committee whether her religion would influence her decision-making. While that incident was captured on film and in official minutes, the case at Stanford is far more murky, with no official record.

“Allegations that any of our endorsees are precluded from affiliating with or receiving endorsements from other groups are unfounded,” the Students of Color Coalition wrote. “We reject the notion that religious or cultural identification might prevent someone from being an effective senator. Such a stance is in direct conflict with S.O.C.C. values.”

Stanford’s undergraduate senate voted in February to ask the university to divest from companies doing business in the West Bank as a way of punishing Israel, but the university’s board of trustees said Tuesday that such a decision would be divisive and it would not take up the matter again.

After her interview with the coalition, Ms. Horwitz filed a complaint with university officials, who met with her and promised a swift investigation.

Lisa Lapin, a Stanford spokeswoman, said that officials had found “conflicting accounts of what occurred” and expanded the investigation after The Stanford Review, a student publication that has criticized the Students of Color Coalition in the past, published an article about Ms. Horwitz. The article also said that the student group had asked candidates it chose to endorse to sign a contract prohibiting affiliation with Jewish groups, and Ms. Lapin said university officials were investigating that as well.

“This is a particularly important teaching moment,” said Vlad Khaykin, the associate director of the Central Pacific Region of the Anti-Defamation League. “Having aspersions cast on their ability to reflect the interest of the student body on the basis that they are Jewish is obviously very troubling to us. The university needs to make it clear to students and student groups that singling out identity and questioning on those kind of issues is discriminatory.”

On Tuesday night, the Students of Color Coalition held what they billed as a “community town hall” meeting at the campus’ Black Community Services Center to discuss the matter; a reporter and photographer from The New York Times who arrived to cover the event were not let in and were asked to leave the area.