The Democratic National Convention will make a mistake of monumental, and possibly lasting, proportions if it puts precedence aside and deliberately renominates a president who, according to the surveys, is destined to lose by a landslide.

Before going down with the Carter ship of state, the delegates should refresh themselves about 1932, when the Republicans made the same mistake. That was the year they renominated Herbert Hoover, although he was clearly doomed because of his failure to cope with the Great Depression. He was crushed by Franklin Delano Roosevelt,who launched the New Deal as the antidote to Hooverism. Moreover, in the long run, the Republican Party suffered an even worse fate: haunted bythe ghost of Hoover, it lost five presidential elections in a row.

Congressionally, the GOP has not to this day been able to make a lasting comeback. In almost half a century, the Republicans have succeeded in winning control of both the House and Senate only twice for a total of four years. The last time was 28 years ago,on the strength of an Eisenhower landslide.

If a forewarned Democratic convention puts loyalty to Jimmy Carter ahead of the best interests of the party and the nation, the decision could have painful effects for Democrats not only this year but well into the future. So many Democratic members of Congress are worried that they will be an endangered species if they have to run this fall with a candidate whose popular standing is the lowest in the history ofpublic opinion polls. Sweeping turnovers occur only infrequently, but when they do they tend to be felt for some time. Over 90 percent of the members of Congress usually win reelection. Hence, if Republican legislative candidates get elected this year because of Carter, it may not be easy to dislodge them in future elections.

The Carter forces keep reminding their delegates that, in this century at least, no incumbent, elected president has ever been denied renomination if he sought it. It is also emphasized that, since Hoover, no incumbent, elected president has been defeated for reelection.

Faced with discouraging popular ratings, both Harry Truman and Lyndon Johnson chose to withdraw voluntarily. As low as they were in the polls, however, they were still higher than Carter is today. But, as can be seen, this incumbent is not the withdrawing type.

It is hardly news that fundamental divisions within the major parties have nearly always led to electoral defeat. The Democrats had been out of power almost continuously after the Civil War until the memorable Teddy Roosevelt-William Howard Taft schismof 1912 resulted in the election of Woodrow Wilson. It is generally agreed that Hubert Humphrey would have defeated Richard Nixon had not the violent 1968 convention in Chicago ripped the party to pieces. Four years ago, the Ronald Reagan-Gerald Ford split probably cost the latter the presidency.

The legality and ethics of "opening" the 1980 Democratic convention can be honestly debated, but in the end the crucial question is this: should the future of one man be put ahead of the future of the party and the nation, both of which have suffered from the blunders of the incumbent?

Of all arguments advanced for openingthe convention, the most telling is that the political climate has radicallychanged since the spring primaries in which Carter captured most of the delegates. Since then, his big lead over Reagan has turned into a grim 28-point deficit, a trend that was significantly reflected in the later Democratic primaries, most of which Carter lost to Edward Kennedy, especially the big states.

"As of today," says Rep. Micheal Barnes (D-Md.), "it appears that the Democratic Party in 1980 is headedfor a historic disaster." Worse, the whole nation may be headed for disaster if the choice comes down to Carter or Reagan. It's been downhill for thecountry ever since the assassination of John F. Kennedy.

His death led to the ascension of Lyndon Johnson, whose Vietnam misjudgements led in turn to Nixon and Watergate, followed by the disappointing regimes of Ford and Carter. Four presidential failures in a row. What have Americans done to deserve such a streak of bad luck?

At the moment, there's only one silver lining. "This whole situation," says Sen. Dale Bumpers (D-Ark.), "is going to sound the death knell of the primary system." Many other leaders inboth major parties would not only agree but add: the sooner the better.