A long blast has come from the depths of a despairing Republican. Sen. Charles (Mac) Mathias of Maryland has enlisted eight other Senate Republicans to demand to know why the Grand Old Party must continue to cannibalize itself, trying to drum out of the ranks even the mildest dissenters from a strictly orthodox Republican line.

The cry is well timed, coming after the debacle in New Jersey. There, Democratic Gov. Brendan Byrne had such a low rating through most of the year that he is said to have considered not running for reelection. He had put over a state income tax and that, in the conventional wisdom, is the death warrant for a governor.

The Republican candidate, State Sen. Raymond Bateman, rated well above the average. Yet Byrne won by 57 per cent of the vote to 43 per cent for Bateman. Democrats now hold 37 state houses to 12 for the Republicans (Maine has an Independent governor).

Mathias's appeal for stopping the cannibalization of his party was touched off by a letter sent to New Jersey voters by a former Republican congressman from that state, John E. Hunt, calling for the defeat in the primary of Sen. Clifford Case, who is running next year for reelection to a fifth term. The chief charge that Hunt, who served three terms in the House, brought against Case in his rather meandering letter is that he wins with the support of liberals and organized labor. Republican conservatives in Massachusetts bring a similar charge against Sen. Eward Brooke of that state.

The Republicans threaten to become a vanishing species. Only one out of five voters is prepared to say he is a Republican. This is a pitiful showing and must be a matter of concern to all of us. A viable two-party system is at the base of our democracy, and that viability has been in question for several years. The basic reason, in the view of this observer, is the conviction of deep-dyed conservatives that the GOP must be shaped in their image.

Large sums are spent by the American Conservative Union and similar organizations to enlist Americans on the conservative side. The assumption is that they will then vote for conservatives. But this does not happen and on the morning after they are left with hurt feelings and a bafflement that their supposed followers have let them down.

Turning back the clock and repudiating virtually everything since FDR and 1933 seems at times to be the stone wall that the conservatives within the Republican Party would erect. Granted, much of what was done under the New Deal and afterward may have been misguided or wrong. The Social Security system, it seems, would have been faced with bankruptcy without the greatly increased taxes recently imposed.

But if the structure of social welfare should collapse, a calamity would ensue that the professional conservatives are ill equipped to counter. It would be a disaster that could hardly be retrieved under the democratic process. Americans are for the most part unwilling to turn back the clock.

There was a time, and not so long ago, really, when the Republican Party expressed the hopes and desires of the great majority. I grew up in Iowa when Republicanism was the official faith. Both my father, who was active in Republican politics on both the national and the local level, and my grandfather believed that Democrats were outside the law and the company of honest men.

Whether Mathias and the liberal-moderates who signed his letter to Chairman William Brock of the Republican National Committee can have any influence in the party is a critical question. To defeat Case and Brooke would be to reduce by two the little band arguing for diversity and moderation.

Many of these same senators sought to persuade Gerald Ford as he began his campaign for reelection that their party was not made up solely of hard-shell followers leaning toward Ronald Reagan. It was a futile attempt. The conservative ghost was to haunt the Ford campaign until the end.