Schmidt holds his own -- for how long?

Helmut Schmidt is now the longest-lasting postwar chancellor since Konrad Adenauer.

How much longer can his nearly eight-year era last?

Asking such questions is a perennial game in Bonn politics. It should be taken with a grain of salt.

In surveys Mr. Schmidt continues to pull the highest approval rating of any West German politician. The 40-plus seat Bundestag (upper house) majority he won in the 1980 election assures his control of parliament so long as his Social Democratic Party (SDP) and Free Democratic Party (FDP) coalition holds together.

Indeed Schmidt may well outlast the current malaise and stay in office until the scheduled general election in 1984. But more observers are beginning to doubt the Schmidt longevity that at the time of his 1980 election was taken for granted.

The current questioning is stimulated by Schmidt's political, economic, and social troubles, and by general bad temper within the government coalition.

Political difficulties include the recent defeat of Schmidt's party in local elections in northern Germany; the political tax scandal that has two Cabinet ministers and Schmidt's own chief of staff under investigation; and constant squabbling between the coalition SPD and FDP and within each of these parties.

The major economic factors are recession-generated unemployment, a continuing drop in workers' living standards, and consequent undermining of the old formula of resolving social frictions by injecting more money.

The main social worry for Schmidt involves the disaffection of many youths who see few job prospects for themselves and too great a prospect of nuclear war. Some are alienated from what they regard as a boring and possibly corrupt society.

The poor showing in March local elections in Schleswig-Holstein is only the latest of a string of electoral and opinion poll defeats for Schmidt's party.

The SPD gets a disappointing 34 percent in opinion polls (as against more than 50 percent for the conservative opposition party). This proportion was confirmed in the Schleswig-Holstein elections. SPD strategists are currently making thekr gloomy post-mortems to try to avert defeat in the four important state elections this year.

The immediate threat is that the conservatives could win a blocking two-thirds in the Bundesrat (federal assembly). The longer-term threat is that the FDP could be encouraged to break its coalition with the Social Democrats and return to its 1960s alliance with the conservatives.

It is this possibility that embitters every quarrel between the classically pro-worker and government-activist Social Democrats and the classically free-enterprise FDP. The major area of bad feeling at present focuses on the job-creation program that the coalition has hammered together. The necessary compromises left both parties feeling they had gotten the short side of the deal.

Furthermore, inner-coalition politics is complicatud by the feuds within each of the coalition parties. Rebellious left-wingers in both parties held rump conferences in March to challenge their own leadership both on the job-creation program and on support for deployment of new NATO missiles if there is no Soviet-US arms control agreement on European missiles in Geneva.

The SPD left-wingers in particular are threatening a free-for-all floor fight on the missiles issue at the SPD convention in April. If Schmidt responds to this challenge by yet another threat to resign, this will only be taken as another sign of his weakened position. On economic issues, Schmidt has been strengthened by the moderate metalworkers' wage settlement.

The metal industry negotiations traditionally set the pattern for other labor talks, and the March accord on a 4.2 percent wage rise (lower than inflation) means that some financial flow toward needed investment can now take place without bitter social confrontation. Expections of economic recovery to a bare 1 percent growth this year, however, still leave a potentially restive 1.6 million unemployed.

In addition to the concern of youth over unemployment, there is also disillusionment over evidence of corruption.

Revelations this year about suspected embezzlement in the trade union federation's housebuilding concern and the official tax-fraud investigation of the Social Democratic finance minister, the Free Democratic economics minister, and Schmidt's chief of staff have fed cynicism.

A kind of German perfectionism has made a number of youths apply their disillusionment to the entire West German political structure and society, with results ranging from rejection of all established political parties to rising applications for immigration to Australia and Canada.

The SPD, which has traditionally enjoyed strong support among the young, is especially hard hit by defections toward small new protest parties that are for environmental protection, against nuclear power and weapons and what is seen as American belligerence, and against such projects as enlarging the Frankfurt Airport.

The SPD is also hit by middle-class defections discontented by the SPD left wing's efforts to cater to political dropouts.