WEST BERLIN, AUG. 9 -- West German Chancellor Helmut Kohl today suffered his first major political loss since the opening of the Berlin Wall when he was forced to abandon his push to advance the first all-German elections from December to October.

For nearly a week, Kohl and East German Prime Minister Lothar de Maiziere had lobbied their respective parliaments to move up the date of both German unification and the new Germany's first election.

The two leaders had argued that the rise in East German unemployment and reluctance of Western investors to pump money into the East's transforming economy required a quick transfer of rule to Bonn.

But today the Bonn opposition, led by Kohl's major election challenger, Social Democrat Oskar Lafontaine, made clear that it would kill the chancellor's proposal. A few hours later, Kohl backed down.

The Social Democrats agree that the economic situation in East Germany requires early unification, but argue that moving up the voting date is an attempt by Kohl to force an election before voters realize that unification will cost far more than the chancellor has said.

The East German Volkskammer, voting at 2 a.m., failed to ratify the proposed election treaty between the two Germanys.

Less than 12 hours later, a heated debate in the West German Bundestag proved to Kohl that he could not get the two-thirds majority he needed to change the constitution to allow early elections.

Tonight, Kohl, his omnipresent smile of recent months replaced by a tight grimace, committed himself to the previously scheduled Dec. 2 election and blamed the Social Democrats for refusing to accept an earlier vote.

Lafontaine, who for many months opposed the ruling Christian Democrats' rush to merge the two German economies, now says quick unification is necessary but only to fix the damage he says Kohl caused by pushing East Germany into a market economy without sufficient preparation.

Unification will cost hundreds of billions of marks, Lafontaine said today in the five-hour parliamentary debate. Addressing Kohl, the challenger said, "You have refused to reveal the costs of unity. You can fool all the people some of the time and some of the people all the time, but you cannot fool all of the people all of the time."

Kohl, who last weekend hinted for the first time that he might have to reconsider his promise of no new taxes to pay for German unity, later reaffirmed his pledge.

But Kohl also announced that Bonn will increase its budget for the third time this year to pay for German unity. The government did not report the size of the budget increase, but economics ministry officials said it would be at least $6 billion beyond the $7 billion already added to Bonn's spending this year.

The economic situation in East Germany is dire. Unemployment has jumped sharply since the West German mark was made the currency of both countries. The number of East Germans on the dole has gone from nearly zero to almost 1 million. The East Berlin government is having trouble paying unemployment benefits, and more plants are closing daily.

But economists here said today that the decline of the East has not been more severe than expected and is a necessary part of the switch from a centrally planned system to a market-based economy.

The political question -- how long East Germans will suffer before taking to the streets once more -- is what worries Kohl and his strategists, and what prompted them to try to move up the election calendar, according to analysts.

But a little public suffering is exactly what the Social Democrats need to have a chance of dimming the chancellor's bright star.

"The situation for the people in East Germany must become worse in order for you to be better off," Christian Democratic Party leader Volker Ruehe told Lafontaine in today's debate.

The Social Democrats would not put it quite that way, but they concede that they need time to have a chance of unseating a chancellor who, according to the latest national polls, 75 percent of the voters expect will win reelection.