A large roster of hard-to-distinguish candidates -- and the splintering that seems certain to characterize the South's Super Tuesday primary next March -- will propel the Democratic Party into an open convention in Atlanta next July.

Having observed the gyrations of the nominating process for 40 years (with roles ranging from that of a precinct committeeman in Tucson in 1948 to the campaign manager of a candidate for president who slogged through most of the 1976 primaries), I am convinced that such a development would be a boon for my party. It would refurbish the process that produced Franklin D. Roosevelt, Harry Truman, Adlai Stevenson and John F. Kennedy by empowering the leaders of the party (including, of course, all of the candidates who have garnered delegates in the caucuses and primaries) to use their collective wisdom and pick a winning ticket just before the big race begins next year.

A convention in which the outcome is not preordained is long overdue. In addition to an overemphasis on primaries, which often activate only a small fraction of the eligible electorate, one of the mistakes made by those who reformed the old system in the 1970s involved new rules that limited the influence of elected officials. Yet any astute member of Congress or governor or mayor has a finger on the local political pulse and has a network of supporters who can sometimes tip the scales in a close presidential contest in a particular state.

I witnessed the impact of the drastic reforms the Democrats adopted before their 1972 convention when I went with Sen. George McGovern to the governors' convention in Houston just after he had defeated Hubert Humphrey in the winner-take-all California primary. These rules (crafted in part by McGovern himself) had largely dealt the governors out of the nominating process. As a consequence, they were bristling with hostility toward the South Dakota senator, and their attitudes in June told me that, barring an electoral miracle, McGovern would lose overwhelmingly in November.

One of the curious things about the myth of the smoke-filled room -- the myth that it is somehow unrepresentative and undemocratic -- is that the history of the past half century does not support the thesis that the old system was manipulated by self-seeking power brokers. The Democratic conventions in 1952, 1956 and 1960 (and the remarkably open Republican conventions that nominated Wendell Willkie in 1940 and Dwight Eisenhower in 1952) are cases in point.

Several prominent senators, the elder statesman Averell Harriman and Vice President Alben Barkley sought the Democratic nomination in 1952. However, once the Republicans had nominated Gen. Eisenhower, Speaker Sam Rayburn and many other party leaders were convinced that the Democrats would lose the White House unless they nominated their best-qualified candidate.

Before the convention a consensus emerged among these leaders that the governor of Illinois, Adlai Stevenson, had exceptional talents for leadership and should be nominated. But the little-known Stevenson did not want the nomination, and the 1952 gathering in Chicago began as an exciting, wide-open convention. Because of unrelenting pressure from Rayburn and other party wise men, Gov. Stevenson finally agreed to run. Stevenson was an eloquent spokesman, and although he lost the 1952 election he ran such a strong race that the "power brokers" of his party readily renominated him four years later.

Kennedy's nomination in 1960 pivoted around a different scenario, but his political exercise also refutes the idea that an open convention is bad for a party and for the country. JFK prevailed in a few primaries to demonstrate that his Catholicism was not an insurmountable handicap. But he won the big prize through a strategy that operated on two levels: he persuaded a half dozen big-state governors to support him, and he put together an enthusiastic grass-roots organization that lined up delegates in most of the nonprimary states. The final votes Kennedy needed to win on the first ballot were nailed down only a few hours before the 1960 convention began.

My hope for a return to rational, commonsense politics is not a pipe dream. A recent reform has already ensured that the Democrats' 1988 convention will be different: a rule change automatically awards delegate seats to 40 U.S. senators and 210 members of the House of Representatives. These new minibrokers could serve as a balance wheel if there were an open convention. They know the strengths and weaknesses of all of the potential nominees, and their professionalism will rule out decisions influenced by images and image makers.

And let me end with a final caveat for the supporters of the candidates already in the field -- and for those governors and senators in the wings nursing a dose of Adlai Stevenson's reluctance. An old-fashioned, open convention does not, ipso facto, rule out the possibility that a candidate who does well in next spring's primaries might win the nomination. Nor does it necessarily imply that a noncandidate will be drafted by the convention.

The spontaneity of an open convention -- and the opportunity it offers to pick the strongest ticket just before the race begins -- could be just the tonic the Democratic Party needs to win in 1988.

The writer was secretary of the interior in the Kennedy administration.