The rescue of the presidential nominating system from the wounds it has suffered in the last 10 years of "reform" is a task whose urgency has been recognized by both national political parties. The Democrats and Republicans have both chartered commissions empowered to recommend changes in public participation, delegate-selection caucuses, presidential primaries and nominating convention rules.

That effort to overhaul the procedures by which we choose the principal candidates for the most important office in the land has been powerfully stimulated and challenged by the report published last week by the Duke University Forum on Presidential Nominations, a bipartisan body including past chairmen and presidential aspirants of both parties and headed by Duke University President Terry Sanford, himself a two-time contender for the Democratic nomination.

The report is addressed to the political parties, and its chief message is that the parties themselves must accept the responsibility for the recent corruption of the presidential nomination process and for its necessary rehabilitation.

In a single paragraph, the report bluntly states why the present system (with its multitude of primaries feeding a mass-media hunger for the hero- candidate whose magical "momentum" will lock up the nomination long before most voters have the contest in focus) "ill serves the purposes of the nation."

"It saps interest, distorts choice, eliminates judgment, narrows the popular base, spans too long a period, and squeezes out of the deliberative process those peers whose evaluations and cooperation the choice of a president vitally requires," the Sanford report says. "Most significantly, the present system radically erodes the foundation of the one institution most necessary to its effective operation: the political party."

Of the five main recommendations Sanford and Co. make, only one is virtually certain to be adopted by the Democratic Party rules commission headed by Sanford's friend and neighbor, North Carolina Gov. James Hunt. That is the recommendation to make members of Congress and other major elected officials automatic voting members of their states' convention delegations.

There will be no great controversy in the Hunt Commission or its counterpart in the GOP, headed by Ernest Angelo of Texas, about two other recommendations from the Sanford group. They are to "revitalize the local party caucus" as the locus for most delegate-choosing decisions, and to "remove every possible barrier to convenient participation" in those caucuses. Those recommendations are very much in the spirit of the rules changes in the last decade.

It is unlikely that the Democrats or Republicans will go as far in restricting primaries as Sanford and Co. would like. Their report suggests that all primaries be squeezed into a four-month period, with one day a month set by party rules for the voting.

That would not only shorten the primary season, it would discourage many states from even bothering to hold primaries. And it would provide the intervals needed to deny those early-primary plurality winners their cheap "momentum" victories the next Tuesday.

That change may be very desirable, but it requires a more massive rearrangement of the election calendar than either party now seems ready to mandate. Still, it is less controversial than the last of the Sanford Commission's recommendations, the one it calls the most vital.

That is simply a call for ending the candidates' veto power over the choice of their own delegates and for freeing all the delegates from binding commitments of support for particular candidates.

That recommendation poses, in the bluntest fashion, the fundamental question both parties must decide: What is the criterion for legitimacy in the nominating process?

The thrust of the "reforms" of the past decade has been to make the convention an automatic device for recording and ratifying the candidate choices already made by participants in the primaries and state conventions.

The Sanford Commission suggests a different kind of convention--one of credentialed representatives of party constituencies, deliberating among themselves on the choice of the best person to head the ticket.

The report says that "freeing the delegates is the key recommendation we bring," because "failure to free the delegates could mean the end of the national party convention as a deliberative body," and that, in turn, would "clearly signal the demise of political parties in this country."

Well, the 1980 conventions and almost all the others since 1952 were anything but deliberative bodies. And somehow the parties have survived. But the issue the Sanford Commission raises is the fundamental one. And the closer the Hunt and Angelo Commissions come to addressing it head-on, the better off the parties and the country will be.