Italy appears to be sliding toward a new political crisis as the minority Christian Democratic government of Premier Giulio Andreotti is confronted by renewed demands for a Communist share in power.

Ironically, these demands have been raised by three non-Communist parties which form the six-party bloc now supporting Andreotti in Parliament.

The current disagreements among the non-Communist popolicitians seem to reflect general confusion about the role the Communist Party should play in Italy's political life. Observers here claim that a growing number of politicians now see the Communists as an acceptable, perhaps even necessary, governing Partner.

The greatest insistence on change has come from the third-place Socialists, the small Social Democratic Party and the tiny, but influential, Centrist Republican Party. The Republican Party is so convinced that the Communists' role must be upgraded, that earlier this mmnth it withdrew its support from a six-party agreement signed last July.

At the same time, there is no lack of die-hard opponents of any greater role for the Communist Party, despite the fact that it is the second largest political organization and a part of the six-party bloc the supporting the Andreotti Cabinet in Parliament.

Against the background of changing opinion toward the Communists, however, political observers here expect that the party's status within the Italian governing structure is likely to undergo changes during the first part of 1978.

There is disagreement about the timetable of future developments, but Italian politicians polled in recent weeks seem to believe that change will probably follow a three-point formula spread out over the coming months or years:

A new one-party Christian Democratic government that would include "technicians" who enjoy Communist support.

The inclusion of the Communists in the "legislative majority, a system already in operation in several of Italy's 20 regions, whereby the Communists vote "yes" on a confidence vote instead of obstaining as at present, but hold no Cabinet posts.

Full Communist particpation in an emergency coalition Cabinet.

One reason for the increasingly openminded attitude toward the Communists is a widespread conviction that the Christian Democrats, Italy's ruling party since World War II, are too weak to govern this troubled country alone.

There is also a noticeable tendency among many centrist politicians to accept the Communists as a bonafide democratic political force. The degree to which Communist acceptability has spread. At least in the Italian political establishment, became evident earlier this month when Ugo La Malfa, veteran leader of the Republican Party, called for Communist membership in the government, claiming that the risks of attempting to govern Italy without the Communists now out-weigh those of governing with them.

La Malfa, who used to chastise the Communists for their close contacts with the Soviet Union, hailed the November Moscow speech of Italian Communist Party leader Enrico Berlinguer as a sign that the party's political vision is "in total contrast with that of the Soviet Union."

Subsequently, Aldo Moro, the Christian Democratic Party's most Prestigious leader, made a speech in which he left the door open for future Communist participation in government. Another former Christian Democratic premier, Amintore Fanfani, put it this way: "When the house is on fire, any kind of fireman will do.

A broad sector of the Christian Democratic electorate opposes a bigger Communist policy role, however, and a group of young Christian emocratic members of Parliament is threatening to leave the party if the Communists are brought in without new elections being held.