After several decades in the wings of major international theaters or in the director's chair on the movie sets of Hollywood or Cinecitta, Italian director Franco Zeffirelli has temporarily abandoned the world of dramatic art to move center stage in Italian politics.

In the Italian national elections today and Monday, the director of "Romeo and Juliet," "Jesus of Nazareth" and "La Traviata" will be running for parliament from his native Florence on the ticket of Italy's dominant Christian Democratic Party, which is fighting to maintain its 1979 level of 38 percent of the vote. Zeffirelli, who credits the Christian Democrats with defending Italy's democratic institutions and acting as an anticommunist bulwark, has not been active in politics before.

This year, however, along with at least a hundred other respected and successful nonpoliticians whose backgrounds range from philosophy and political science to union organizing and ownership of a soccer team, Zeffirelli accepted when the Christian Democrats' dynamic new leader, Ciriaco de Mita, asked him to run.

The recruitment of nonpoliticians into the ranks of Christian Democratic candidates is a crucial element of de Mita's ambitious attempt to revamp the party by replacing worn faces and old policies. De Mita took over as party secretary in May 1982 and, according to the polls, has been making good on his determination to patch up the party's scandal-plagued image.

In power without interruption over the last four decades, during which the party has led all but two of Italy's 43 governments, the Christian Democrats are currently under attack by both their Communist opponents and their Socialist allies for being excessively conservative and for failing to stabilize the country's sliding economy.

De Mita's approach appears to be paying off. While a year ago conventional wisdom was predicting a sharp drop in the Catholic party's political fortunes, the latest polls indicate that overall losses may be minor.

Zeffirelli, 60, who considers de Mita "an exceptional politician," says the Christian Democrats are trying to offer Italians "a new way of conducting politics." De Mita and other party leaders had become convinced, he says, that the Christian Democrats were losing touch with Italian society and decided it would be beneficial if nonpoliticians from all walks of life were to become politically involved.

Last week de Mita proposed meeting after the elections with the Socialist, Republican, Liberal and Social Democratic parties to work out the basis for a new five-party coalition. But as the three-week campaign drew to a close, acrimony between the Socialists and the other parties became so sharp that de Mita's plans were thrown into doubt. It appears that the country's 44 million voters are going to the polls not only in their customary ignorance of the identity of the next prime minister, but also in the dark about the political complexion of the country's next government.

The offer of candidacies--sometimes secure ones--to esterni, or outsiders, has been a key tactic in the Christian Democrats' attempt to hold or add to their current 261 seats in the Chamber of Deputies and 138 in the smaller Senate. The decision to replace 20 to 30 percent of the party's previous candidates, as well as purge politicians involved in past scandals or present judicial investigations, reflects de Mita's conviction that without a "new face" the Christian Democrats cannot hope to maintain their dominant role in Italian politics.

De Mita, 55, has sought to revise party practice by giving key appointments to technocrats rather than party regulars, and by speaking out frankly about the Christian Democrats' past failures. His budding reputation as a modern politician was further boosted a few months ago when he made a comment, unusual in Italy, that the real distinctions for policy-making ought to be between old and new policies rather than between right and left.

For Zeffirelli, who has postponed work on a new film about the Renaissance Florentines and on preparation for a 1985 production of Tosca at the Metropolitan Opera in New York, the shift in party policy has meant more than 80 tiring political rallies and meetings in Florence, where the campaign has centered on cultural and artisan- labor problems. Other Christian Democratic esterni of varying professional backgrounds have focused on different issues.

For Guido Carli, until 1975 the head of the central Bank of Italy and subsequently president of Con Industria, the Italian national association of manufacturers, the major theme has been backing the Christian Democrats' calls for economic "rigor" as a means of dealing with double-digit inflation and huge budget deficits.

Carli, 58, is running as an independent on the Christian Democratic ticket in a big-money district of Milan, and, if elected, is likely to be offered one of the Cabinet's major economic or financial posts. Never before engaged in active politics, Carli last week told the Milan daily La Notte that he had agreed to de Mita's offer because he wanted to stop living as "a privileged observer."

"This is a time in which the support for the party is needed from someone like myself who tends to look for rational solutions to problems," he said.