Harvard Law School student-volunteers call registered Massachusetts voters from the Casperson Student Lounge on Sunday night in support of Elizabeth Warren, HLS professor, in her campaign for US Senate.

Wielding cell phones and markers, nearly 70 Harvard students helped to launch on Sunday night the first major on-campus event on behalf of Law School professor Elizabeth Warren’s campaign for U.S. Senate.

While the crowd of mostly law students mingled, debated, and made posters, the majority eventually took to the phones on behalf of the candidate who just a few months ago was at the blackboard.

The joint phone bank and information session was organized by “HLS for Elizabeth Warren” and was the first time a student group on campus held a large event on Warren’s behalf.

The roughly 70 volunteers made about 2400 phone calls to residents of Cambridge and Newton, gauging interest and offering information about Warren and her upcoming campaign events.

Warren’s husband, Harvard Law School professor Bruce H. Mann, and a friend, Law School colleague Jody Freeman, spoke briefly to the volunteers about Warren and her goals in between calls.

“This is probably the marquee election in the country,” Freeman told the crowd. “The Senate is a place that often finds itself stuck.... Elizabeth is a person who can really be a game-changer.”

As a nonprofit, the Law School cannot endorse a political candidate or issue, but many law professors have rallied around Warren with moral and financial support, Mann said.

“She’s taught here a long time,” Mann said. “To know that she has the support of her students means a great deal to her.”

That the event should be hosted by Law School students came as little surprise to most students at the event.

The group’s size—roughly 350 members—and its prominence on the Harvard campus points to the unique relationship the Law School has with the woman who was an active professor last semester.

Students in the College have formed their own group in support of Warren, and mainstay Democratic groups on both campuses are likely to endorse her. But the law students in support of Warren have positioned themselves as the leaders on campus, based primarily on their familiarity with the longtime law professor.

“I do know a lot of people who might not support Professor Warren if they didn’t know her,” said Law School student Ben Cluchey, an “HLS for Elizabeth Warren” organizers who had Warren as a professor last fall. “But she commands an enormous amount of respect if you do know her.”

Volunteers said that Warren’s personal appeal among law students is underscored by the universality of her message and her work as an academic and an advocate of the middle class.

“I definitely think [support] crosses party lines. I think part of that is that she’s a professor here, but also just attributable to her,” said Law School student Alyssa Martin, one of the event’s organizers.

—Staff writer Nicholas P. Fandos can be reached at nicholsfandos@college.harvard.edu.