Italy's governing center-left coalition resigned today, paving the way for early general elections expected to take place in June.

The downfall of the 43rd Italian government since World War II became inevitable after the Socialist Party announced last week that it was withdrawing its support for the Christian Democratic prime minister, Amintore Fanfani. Socialist leaders hope that their party will be the major winner in the next elections.

President Sandro Pertini accepted the government's resignation during an audience with Fanfani following an acrimonious debate in Parliament. The president has attempted frequently in the past to persuade the squabbling politicians to patch up their differences, but this time he appeared to have no choice but to agree to new elections, officials said.

By consensus of the major parties, the elections are likely to take place on June 26, one year ahead of schedule. It is the fourth consecutive time that an Italian Parliament has not run its full term.

Government crises in Italy often have been triggered by outside events such as political scandals or economic difficulties. The present crisis instead was due almost entirely to the rivalry among the political parties that make up the coalition, particularly the competition between the dominant Christian Democrats and their largest partners, the Socialists.

Socialist leader Bettino Craxi, who was responsible for triggering the crisis, is regarded by most political observers here as a dynamic politician with ambitions to be prime minister himself in a new center-left government. This could be possible if the Socialists, who won just under 10 percent of the vote in the last elections in 1979, pick up another couple of points.

The principal explanation given by Craxi for withdrawing from the coalition was not that the government had failed in its duties but that elections were inevitable so they may as well be held sooner rather than later. Italians already were scheduled to vote on June 26 in regional and municipal elections.

The Socialists owe their tactical strength in Italian politics to their position as the principal swing party, wooed by the two largest parties, the Christian Democrats and Communists. The Socialists are necessary in any centrist government that excludes the Communists, who lead the opposition.

It is widely predicted that the Communists will again lose votes after falling to 30 percent in 1979 from a peak in 1976 of 34 percent--just three percentage points less than the Christian Democrats.

The Communists' present electoral strategy is based on promoting a left-wing alliance with the Socialists after a period from 1976 to 1979 when they tacitly supported a coalition led by Christian Democrats.

The Socialists, however, have ruled out a coalition to their left for the time being. They would be swamped by the electorally more powerful Communists, unlike in France where the Socialists play the dominant role in a left-wing coalition.

The ruling coalition that resigned had included the Christian Democrats, Socialists, Social Democrats and Liberals. Fanfani was expected to remain prime minister in a caretaker capacity until the elections.

An Italian news agency reported that the neofascist Italian Social Movement had asked the son of former dictator Benito Mussolini, 65-year-old Vitorio Mussolini, to run in the elections as one of its candidates. The neofascists regularly pick up 5 percent of the votes in Italian elections.