Richard G. Sterns, a first year law student, will testify this morning at 10 a.m. before the Senate Select Committee on Presidential Campaigning--the Senate Watergate Committee.

Sterns, a 1968 graduate of Stanford and a former Rhodes Scholar at Oxford, was deputy campaign manager and western regional coordinator for George S. McGovern's presidential campaign. He was subpoenaed Tuesday during a class at the Law School and ordered to appear in Washington within two hours.

In a telephone interview from Washington yesterday, Sterns called the issuance of the subpoena "a Republican effort to sustain themselves following three months of damaging testimony."

"This is the best they have been able to do," he said. "In the end their final defense will probably be--'everyone does it.'"

He called the Republican efforts "a fishing expedition."

Outrageous Subpoena

Sterns called his subpoena "outrageous."

"Several groups used the McGovern Election Committee's telephones and placed leaflets in McGovern headquarters in Los Angeles," he said. "Does this prove that the McGovern Campaign Committee initiated the demonstrations?"

He said that the Senators on the Ervin Committee were "getting bored" with the inquiry and were "reluctant to put me on," and that he expects to be back in Cambridge by early afternoon.

The Ervin Committee bears the expenses Sterns has incurred in travelling to Washington, but he said that he was losing valuable time by being away from school.

In Cambridge, McGovern's chief speech writer, Robert Schrum, a fellow at the Institute of Politics, echoed Stern's charge that the Republicans on the committee were engaged in a "fishing expedition, adding "they (the Republicans) have to be desperate to compare actions such as the Ellsberg burglary and wire tapping with Dick Tuck's pranks."