Opposition Gropes for Clues to Loss of Votes : Cardenas and his battered Democratic Revolutionary Party are doing some soul-searching after yet another defeat.

With his party badly beaten in midterm federal elections last week, Mexico’s populist leader Cuauhtemoc Cardenas looks a little like Charlie Brown after Lucy has pulled the football out from under him one more time.

Cardenas, who many Mexicans believe was robbed of the presidency three years ago, continues to play ball with the ruling party: He participates in elections, loses ground each time and cries foul when the vote turns out to be less than fair.

“We are trying to change the rules of the game in favor of democracy,” said Cardenas’ chief adviser, Sen. Porfirio Munoz Ledo. “But it hasn’t been possible. This time the state committed new fraud. What can the opposition do in the face of this?”

Cardenas’ Democratic Revolutionary Party is flailing for answers to this and other questions. While publicly blaming the government for their problems, party leaders are searching for explanations of how they lost so much support and, more importantly, how to get it back in clean elections.

By official count, Cardenas won 31% of the vote in 1988’s presidential election, leaving successful nominee Carlos Salinas de Gortari with a little over 50% of the vote--the lowest ever margin of victory for a candidate of the ruling Institutional Revolutionary Party. A coalition of parties backing Cardenas won 139 of the 500 seats in the Chamber of Deputies and four seats in the Senate, the first in that body ever gained by the opposition. Mexico City and the states of Mexico, Morelos, Michoacan and Baja California came out for Cardenas.

The ruling party, called the PRI, immediately began chipping away at the power base of the man who also happened to be the son of Mexico’s historically most popular president, Gen. Lazaro Cardenas. In 1989, the government conceded defeat to the conservative National Action Party in Baja California’s gubernatorial race while claiming victory in Michoacan state and in municipal elections that most observers considered to be fraudulent.

The PRI recovered its edge in Mexico state elections last year and in Morelos this year. Those elections appeared to be more honest, but by and large a disillusioned opposition stayed away from the polls.

Meanwhile, Cardenas’ coalition broke up--after the PRI persuaded one of its old satellite parties to return to the fold. Cardenas formed the Democratic Revolutionary Party from among PRI dissidents such as himself and members of the former Mexican Communist Party, retaining 51 of the coalition’s 139 seats in the Chamber of Deputies.

The new party, called the PRD, was beset with divisions, primarily between those who wanted to maintain a combative posture against what it called an “illegitimate” government and those who favored negotiating a transition to democracy with the PRI administration and other political groups.

A few of the party’s best minds left in frustration. Jorge Alcocer, a former Communist Party member, resigned in December, charging the PRD was undemocratic and lacked a clear program.

Infighting over who should be this year’s PRD candidates created further disarray. Then, just three days before the election, the government delivered its most embarrassing blow, announcing that the PRD’s congressional leader, Ignacio Castillo Mena, would become Mexico’s new ambassador to Ecuador.

Finally, in the Aug. 18 election, the PRD received just 10% of the vote nationwide. The party didn’t win a single district outright, although it will have 41 deputies based on the proportional vote. The PRI retook Mexico City, the nation’s power center.

Munoz Ledo blamed the beating on fraud--vote buying and stealing. “We weren’t defeated,” he said. “Under these circumstances, the possibility of competing in elections is practically null.”

But PRD defector Alcocer said the problem is that the PRD was passive. “The PRD was counting on the failure of Salinas’ policies. Any party that aspires to government must have a program of its own and not wait for the cadaver of its adversary,” Alcocer said.

“They had this magic thinking that they didn’t have to organize because the people are Cardenista ,” he said. But, he added, the election shows that most voters in Mexico are not wedded to a single party and, therefore, could be won back.

PRD leaders hold out the threat of withdrawing from future elections, but privately they admit that it would be political suicide.”We need to build civic coalitions based on a proposal for democracy,” PRD spokesman Ricardo Pascoe said. “We are up against an institutional dictatorship and the way to combat a dictatorship is to unite.”