Schmidt tries to mend his party's fences

West German Chancellor Helmut Schmidt appealed to his party's left wing April 20 to abandon moral absolutism and avoid helping ''neoconservatism'' by default.

Without addressing them by name, he also called on antinuclear activists to avoid endangering Soviet-American arms control negotiations by promising Moscow a unilateral NATO renunciation of new nuclear weapons in the absence of any treaty binding both East and West to limitations.

In his three-hour speech at the Social Democratic Party (SPD) convention Schmidt defended in addition the option of nuclear power and the government's modest job-creation program, other policies vigorously opposed by the SPD left wing.

At the heart of his argument was the specter of an SPD fall from power and the return of a conservative government after a dozen years of Social Democratic-Liberal rule.

It was this specter that gave Schmidt a resounding victory against conservative right-wing candidate Franz Josef Strauss in the October 1980 election. The absence of this specter in local and regional elections since then has given the SPD its poor showing, with votes (and public opinion polls) dropping the party down to percentages in the mid-30s.

Behind this unfavorable trend is a crisis that is eroding the SPD on both sides of its center. On the one hand the SPD is losing voters (primarily young ones) to the new environmentalist and antinuclear movements to the left. On the other, as the SPD left wing turns more uncompromising to attract these voters back into the fold, the party is also losing a bloc of West German voters in the center, who fear a leftward swing in the SPD.

It was to the middle that Schmidt appealed squarely in his convention speech. Moral absolutism is admirable, he acknowledged. But when it leads to rigid rejection of compromise on issues of nuclear weapons, nuclear power, and economic policy, then it simply serves an eventual restoration of the neoconservatives.

The left wing, he continued (while avoiding explicitly naming the left wing), must not set itself self-righteously above West Germany's voters, above the SPD majority, above the Liberal coalition partners, above the American ally. The essence of democracy is compromise. Failure to respect this principle led to the factionalism and weakness of democrats in Weimar Germany and the consequent rise of Hitler, Schmidt noted.

The SPD left wing has perhaps been sobered more by the voter disenchantment evident in local elections than by Schmidt's steady preaching of the message of ''common sense,'' ''pragmatism,'' and ''realism.'' The expectation is that the SPD moderates will be able to carry Schmidt's platform on the three key issues at the convention.

If so, Schmidt will not resign, as he has threatened to do if his party rejects his pursuit of both arms control negotiations and the intention to station new NATO nuclear weapons in West Germany.

Schmidt's resignation on this issue would lead to the breakup of the Social Democratic-Liberal coalition--and either a new Conservative-Liberal government or new elections in which the SPD clearly would lose heavily.

Despite Schmidt's expected garnering of an unenthusiastic majority at the convention, the intraparty strife is hardly over. The leader within the SPD of the fight for a unilateral rejection of new nuclear weapons, party executive committee member Erhard Eppler, has just vowed to take his opposition outside the party if necessary.