Presidential hopefuls George McGovern, Edmund Muskie and Rep. Paul N. (Pete) McCloskey will address a voter registration rally this afternoon at Government Center. The rally is slated to begin at noon and will continue until 6 p.m.

Also appearing at the rally will be Rep. John Conyers (D-Mich.), Allard K. Lowenstein Rep. Donald Riegle (R-Mich.) and John Kerry, a leader of the Vietnam Veterans Against the War. Entertainment will be provided by Peter Yarrow and John Denver.

The city of Boston is providing 100 voter registrars for the rally. Speakers will begin at 1:45 p.m.

Another rally is planned at noon today at the Cambridge Election Commission office, 362 Green Street in Central Square. Speaking at the "register-in" will be Kerry and Rep. Robert F. Drinan, S. J. (D-Mass.)

The Cambridge rally will be held without the benefit of voter registrars. Thus far, the Board has resisted efforts to register students.

Should the election board turn back students attempting to register on masse, the Cambridge Committee for Voter Registration hopes to press another lawsuit against the board for discriminatory practices.

Michael Segal, a spokesman for the Boston rally group, stressed the potential power of the youth vote. "Young people could run everything, if only half of them voted in any election," he said.

He added that he expected today's rally to stimulate voter registration here, "as similar rallies have done everywhere else in the country."

Massachusetts Voter Registration Coalition will also distribute "pledge cards" through which students will pledge to work for candidates committed to immediate withdrawal form Vietnam and to new priorities.

Curt Mead, press coordinator for the rally, declined to make a crowd prediction. He did say, however, that a crowd of fewer than 8000 "would be an extreme disappointment," and that the committee would be extremely pleased if more than 15,000 showed up.

In a colloquy with a student at the press conference, Sen. Edward M. Kennedy '54, (D-Mass.) said he believed change could be brought about by governmental action. You can affect people's lives," Kennedy said. He cited civil rights, hunger programs and legal aid for the poor as examples of such governmental action.

On another subject, Kennedy said he hoped that President Nixon would appoint Supreme Court justices committed to "progressive, liberal thought."

He added, however, that he doubted the Senate would reject an appointee on the basis of his philosophy alone. "Many of the great giants wouldn't have been approved if that had been the criterion," he said