Spaniards are learning that democracy is not an unmixed blessing. They have found it to be a much more complicated and exhausting business than anyone imagined.

Just last Dec. 6 they trooped to the ballot boxes to express their approal of the new constitution. On March 1, elections will be held to select a new parliament. Its composition will determine which party is to govern the country for the next four years. A month later, on April 3, they are to vote yet again, this time for new mayors and city councilmen.

Even after this ordeal the formation of a strong, effective government is by no means assured.

The outcome of the March 1 balloting is likely to be crucial in setting Spain's political course for some years to come. Since the first post-Franco elections in June 1977, political life has been dominated by two parties, the Union of the Democratic Center (Ucd/) -- a center right party -- led by Prime Minister Adolfo Suarez, and the Socialist Workers Party (PSOE), under the leadership of Felipe Gonzalez. The two parties are evenly matched in terms of popular support, and their leaders both enjoy great popular esteem.

The election campaign officially begins on Feb. 7. It is expected to be a hard-fought one, and the final outcome will probably be close. Polls during the past year generally suggested a loss of UCD support and a corresponding gain for the Socialists. This trend reflected growing concern over high unemployment and economic recession. Had the election taken place then, PSOE would probably have emerged as the country's leading party.

But in recent weeks the polls have registered a perceptible shift in voter preferences. The endless cycle of terrorist assassinations in the Basque provinces and elsewhere and the recent aborted coup by a group of disgruntled military officers are most responsible for the change. Public concern for law and order has increased, and such a trend invariably fosters a more conservative political modd.

The UCD thus enters the contest with the initial advantage. Yet great insecurity prevails over the final outcome for a number of reasons. Felipe Gonalez is a formidable campaigner, charismatic and intellignet. Furthermore, voter behavior has tended to be highly volatile, and voter participation is also on the decrease, reflecting a growing disenchantment with politics. Finally, the Socialists are expected to gain control of the mayoralties of many large cities in the April municipal elections, resulting in an appreciable loss of authority for any future UCD government.

The probability is that neither party will emerge with a parliamentary majority, necessitating the etablishment of a coalition government.

Should the UCD win but fall short of a parliamentary majority, the formation of a strong government is impossible without the participation of the Socialists. Other parties may not be able to furnish the additional seats required, or the political price they demand may be too high. There are also the Communists, who prefer Suarez to Gonzalez, but whose formal support would be a distinct liability.

In the event of a Socialist victory, Gonzalez too could expect difficulties in forming a multi-party government. Given the small likelihood of garnering a parliamentary majority, Socialist strategy envisages a coalition composed of the Basque and Catalonian regional parties and the UCD's Social Democratic faction. But this seems a risky undertaking.

The alternative then would be a UCD-PSOE collaboration, the "Grand Coalition." Its advantages are all too clear. It could count on the overwhelming support of parliament, and its legislative and economic programs would consequently encounter little formal opposition. But the Socialists are not now inclined to serve as junior partners in such a union. To do so would generate internal party divisions; the Communists may succeed in making inroads on its left, and aprticipation could prejudice PSOE's future prospects.

Suarez also dislikes this kine of political matrimony. The traditional Spanish right, thus far in disarray, is now showing signs of regrouping. A coalition with the Socialists at this time might therefore result in defections on the right. Furthermore, his party is a hodgepodge of diverse political groups, and to collaborate with the more cohesive PSOE could prove its undoing. Understandably, neither pary presently favors the "Grnad Coalition" formula.

But therein lies the rub. Should neither party come out of the March 1 election with a clear mandate to govern alone, a difficult situation will ensue. If Suarez narrowly wins the election, which is the present betting in Madrid, he may be able to assemble a coalition without the Socialists. It is, however, likely to be a weak and ineffective one, an eventuality that could imperil the democratic consolidation. Suarez and Gonzalez may then be obliged to undertake an "agonizing reappraisal." The painful dilemma of Spanish politics is that the two major parties can live neither with nor without each other.