King Juan Carlos I called the leaders of Spain's political parties together today for a private, preelectoral meeting that reflected the nervous expectation with which Spaniards await the vote Thursday for a new government, and the sense that it could mark the beginning of a new era here.

The last time such a meeting took place was Feb. 24 last year, the day after a group of soldiers, led by Civil Guard colonel Antonio Tejero, burst into a session of the Congress and tried to take over at gunpoint.

Juan Carlos aborted the coup attempt by going on national television and declaring -- as it turned out, correctly -- that the military was backing him against the rebel guardsmen. But, as he reportedly warned the politicians he met with the next day, it was a gamble that would not work twice. Whatever their differences, Juan Carlos told the political leaders then, the most important thing was that they avoid provocation and work together for the stability and continuity of Spain's fragile democracy.

It was an appeal they appear to have heeded, even during the disintegration of the ruling centrist coalition last summer. Despite occasional rumors, the discovery of at least one plot, and alternating campaign charges of coup-mongering and imminent communist takeovers, the race has been relatively free of saber rattling and smears.

And despite the fact that the military has been placed on alert for the elections, the politicians emerged from the Zarzuela Palace this afternoon saying that the crown expects everyone to respect the constitution, and that the king believes that "95 percent" of all Spaniards are facing election day with "tranquility."

But the real test of long-term democratic stability here, Spaniards of all political stripes agree, will come in the weeks and months after the vote. If the polls and the sense of the street are right, the overwhelming victor will be the Spanish Socialist Workers' Party -- giving Spain its first Socialist majority government in history and, just seven years after dictator Francisco Franco's death, the first left-wing administration since the Spanish Civil War.

"The month after the elections," and before the new government is to take over in December, said one local political commentator, "is very dangerous. That's when it sinks into the Army." In addition, "there could be an increase in terrorism" from Basque separatists, "an attack against the pope" during his visit here next week, "or massive destabilization" by the holders of the country's economic reins.

Felipe Gonzalez, 40, the charismatic Socialist leader, says he is certain Spain is ready for the "true democracy" this election represents. Like Gonzalez, most of the Socialist leaders were university students in the 1960s whom Franco forced underground or out of the country. There, many attached themselves to liberal and leftist activism in Europe or the United States. While their opponents brand them as far to the left, they say they feel akin to West Germany's Social Democrats or the Greek Socialists.

While the Socialists have talked of change, the Popular Alliance headed by Manuel Fraga has appealed to those who are afraid of it, and has promised to defend the institution of the family, protect the armed forces and lower taxes. Fraga has warned that socialism "would set Spain back centuries."

But the program offered by the Socialists, who officially dropped the term Marxist from their name when Gonzalez threatened to quit over it three years ago, is a self-consciously moderate one. The only nationalization they propose is of the nationwide electrical grid and they declare they can help business and industry more than the right because of their good relations with organized labor.

All of the parties have labeled unemployment, now at 15 percent nationwide, a priority, and the Socialists have pledged 800,000 new jobs over the next four years. Vowing not to raise taxes, they say they will get the money to prime the pump of the stagnant economy by eliminating fraud in the tax collection system.

There is conservative concern over Socialist advocacy of more control and funding of public education in this country, where the state still heavily funds private, primarily religious schools. The Socialists promise that "freedom of education doesn't mean Socialist education," according to Madrid congressional candidate Juaquin Laguina. "It means freedom from ignorance" and equal educational opportunity.

Gonzalez advocates a "step-by-step, progressive reform" of the top-heavy Army -- there are 70,000 officers in the 240,000-man force -- but promises to foster a new respect from the public, modern weaponry and backing against terrorism.

The Socialist foreign policy program is one of neutrality between the superpowers, with close ties to Latin America and the Arab world and a pledge to increase efforts to negotiate Spain's entry into the European Community. A pledge eventually to hold a referendum over withdrawal from NATO, which Spain joined just last summer, is likely to cause a run-in with Washington. Still, Gonzalez told a group of reporters Monday that he wants "close, good relations with the United States," which uses four naval and Air Force bases in Spain.

Fraga has hinted that the Socialists are, like their leftist predecessors in the republic, anti-monarchist. Gonzalez, who recognizes Juan Carlos as the principal glue that has held the country together, has found it necessary this week publicly to declare his fealty to the king.