New voters are registering, and old voters are changing their party affiliations in record numbers in anticipation of the April 30 Massachusetts presidential primary.

In Cambridge 2332 new voters have registered since the last election--most of them as Democrats. In a comparable period before the 1964 primary, there were only 1000 new registrants.

There have been 270 changes in voter registration in Cambridge--nearly all of them from Republican to either Democrat or Independent. In the 1964 primary, there were 2425 Republican votes in Cambridge. It is highly probable that about 10 per cent of the Republican primary voting strength has changed sides.

Similar changes occurred in the suburbs. In Brookline, where the total vote in the last primary was 4570, 336 have left the Republican party. In Newton, where the election turnout is expected to be about 10,000, the Republicans have lost 675 voters.

Across the state, those leaving the Republican camp out-number those leaving the Democrats by about four to one.

These statistics show a strong trend in voter support for Sen. Eugene J. McCarthy. Although victory seems secure, there has been no let down in McCarthy's campaign; his forces want the clearest possible victory.

Robert F. Kennedy '48, is allowing a quietly organized write-in campaign to be conducted on his behalf. Should he draw an unexpected vote, he can take the credit. If he doesn't, he can say he had promised to support McCarthy. Either way, Kennedy can lay claim to part of the vote.

Neither Richard M. Nixon nor Nelson A. Rockefeller wants any trouble with Volpe, the only candidate on the Republican primary ballot. Both candidates are working to win the governor over.

With Nixon and Rockefeller out, Republicans who dislike Volpe or missed the change of registration deadline of March 30 have no one to vote for.

To capitalize on this situation, candidate McCarthy has commissioned the Coalition for McCarthy under Justin L. Wyner to conduct a Republican write-in campaign for him. If successful, it would be a strong show of bipartisan support for McCarthy.

Wyner thinks the "Republican vote will be the most significant vote McCarthy gets" in Massachusetts. "It is a vote to which Kennedy can lay absolutely no claim," he said.