The first busload of 38 Harvard and Radcliffe students and other area residents left Cambridge for Washington, D.C., last night to lobby for the Administration's civil rights bill.

They will spend the day meeting with a number of key Senators, urging them to work for the prompt passage of the bill without weakening amendments, and will return to Cambridge into tonight.

When the group arrives in Washington tomorrow morning, it will meet with a member of Senator Humphrey's staff. He will brief the lobbyists on the contents of the House-passed civil rights bill and on the nature of the proposed amendments, and he will describe the positions of the Senators who will be approached by members of the group.

The lobbyists will then visit 35 Senators whose positions on the civil rights bill are considered "equivocal" and present them with petitions. The legislators who will be approached include Barry Goldwater (R-Ariz.), Everett Dirksen (R-III.), Frank Lausche (D-Ohio), Albert Gore (D-Tenn.), Karl Mundt (R-S. Da.), and John Tower (R-Texas).

The trip was organized by the United Ministry at Cornell University and is sponsored by the Lendership Conference on Civil Rights, the Northern Student Movement, SNCC, and other civil rights groups.

Another busload will leave tonight to spend Tuesday in the Capitol. Leaders hope to have similar busload of students and other interested people arriving in Washington all week.