By William Branigin
Washington Post Foreign Service
Sunday, September 11, 1988; Page A30

MEXICO CITY, SEPT. 10 -- Carlos Salinas de Gortari, the 40-year-old standard-bearer of this country's long-ruling political machine, was formally declared president-elect of Mexico today after two days of bitter, sometimes raucous, debate in the Mexican Congress.

The 500-member Chamber of Deputies, the house of Congress charged with ratifying the results of Mexico's July 6 presidential election, passed a resolution this morning rejecting opposition charges of massive vote fraud and proclaiming the "legitimate triumph" of Salinas in the most hotly disputed national contest in Mexico this century.

The tally of 263 to 85 was along party lines, with all the deputies of the ruling Institutional Revolutionary Party (PRI) voting in favor. Members of the conservative National Action Party voted against the resolution, and deputies supporting leftist opposition presidential candidate Cuauhtemoc Cardenas walked out rather than participate in what they called "an illegitimate act." Cardenas, 54, a former PRI state governor who split from the party last year, claims he was cheated of victory through widespread, systematic vote fraud.

Cardenas supporters warned after the vote that their struggle, having exhausted all legal means of challenging the official election results, now would enter a new phase of protest with unpredictable consequences. Cardenas has called for a rally Wednesday in this capital's central plaza to launch the new stage of protests.

Today's vote, which followed an all-night session of filibustering by opposition deputies, took place in relative tranquility compared with a stormy session Thursday night in which legislators shouted obscenities at each other and scuffled on the rostrum when the PRI tried to push through its resolution. The opposition succeeded in delaying the proclamation of Salinas but in the end could not prevent it.

After the vote, the PRI legislators trooped to Salinas' house to congratulate him. Salinas, a Harvard-educated economist and former planning and budget secretary in the current PRI government, was chosen last year by outgoing President Miguel de la Madrid as the PRI nominee in a system that enables a Mexican president virtually to designate his successor.

Salinas, who is scheduled to take over from de la Madrid on Dec. 1, has been keeping a low profile lately. Essentially, he has allowed party hard-liners who have been at odds with his reformist ideas to take the lead in ramming through today's final step in the protracted electoral process.

Throughout that process, the PRI, which has never lost a presidential election in its 59-year history, consistently refused opposition demands for a recount in the presidential vote. In a statement Monday, PRI president Jorge de la Vega Dominguez accused opposition parties of adopting "an immoral and perverse attitude" by charging fraud even before the elections were held. "Their objective is simplistic and puerile: the conquest of public power through provocation, confusion, disorder and destabilization," he said.

The final results ratified today showed Salinas winning with 50.74 percent of the vote, followed by Cardenas with 31.06 and National Action Party candidate Manuel Clouthier with 16.81 percent. Some Mexican and foreign diplomatic analysts said they believe Salinas indeed may have won the election, but only with a narrow plurality of, at best, around 40 percent. However, any result giving a PRI presidential candidate less than half the vote is seen as unacceptable by the party, the analysts said.

"Salinas is now the hostage of the most retrograde, conservative, backward, closed sectors of the PRI," said political scientist Jorge Castaneda. "It's ironic that the election of someone who says he's going to reform the country has to be ratified virtually by brute force."

During last night's debate at the Chamber of Deputies, riot police sealed off streets around the building and barred public access to it after several thousand Cardenas supporters gathered for a noisy rally at the front entrance.