"They're at it again," said a middle-aged woman whose tone betrayed a mixture of dislike and grudging admiration.

She was pointing at a young man with a megaphone, a member of Italy's small but active Radical Party, who stood in Rome's spacious Piazze Navona energetically exhorting passersby to "sign here if you want to force Parliament to enact the reforms our constitution guarantees us, abolish the Concordat with the Vatican, change the military code and end public financing of political parties."

Nearby, other party workers at hastily set-up chairs and tables were busy coaxing signatures supporting an eight-point civil-rights referendum.

With only a couple of weeks to go, volunteers from among the party's 4,000 militants have already collected almost all the 500,000 signatures needed for a popular referendum that, by abolishing eight major Italian laws, could totally overhaul some of this country's basic institutions - including its traditional relationship with the Roman Catholic Church.

The chief sponsors of the successful Italian divorce drive and the most active supporters of the continuing abortion fight, the radicals are confident that their reliance on direct democracy will pay off once again.

Their eventual success in completing the petition, and in getting out the vote next spring if the referendum is held, could also confirm some forecasts that this increasingly anti-Communist group of highly vocal social reformers will play a growing role in Italy.

Some observers, including several U.S. government officials, are convinced that because of the small party's non-ideological character, will eventually increase its current 1 per cent of the vote to become the nucleus of a liberal but non-Marxist party.

"Others say the Radicals, with their past support for drug reform pacifism, linguistic minorities and ecology, at least comprise an effective pressure group.

"But lately they seem to be moving into the other camp," said a Christian Democratic deputy in reference to the party's ever-closer ties with left-wing extremists.

Other Italian policy-makers feel that the Radicals have too piecemeal an attitude. "They generally ignore economics and have no comprehensive program for society as a whole," said an economist.

Nevertheless, the Radicals are almost the only party now in Parliament to win significant approval from Italy's politically disillusioned youth, as well as from several "extra-parliamentary" leftist extreme groups.

The 400,000 votes won by the party in last year's elections - the first for the Radicals - also came from disgruntled former supporters of such traditional parties as the Communists, the Socialists and the right-of-center Liberals. The Liberals fathered the Radical movement back in 1956.

Other backers, according to a recent poll, are people without previous political ties attracted by the party's pragmatism, intransigent anti-clericalism, concern for individual freedoms and opposition to the compromise between the ruling Christian Democrats and the second-largest party, the Communists.

The party's four representatives in the Chamber of Deputies have exploited that body's rules to attack the Christian Democrats and the Communists vociferously.

Accusing the Christian Democrats - in power for more than 30 years - of corruption, bad government and betrayal of the community's interests, the Radicals favor a left-wing coalition.

The Radicals are even harsher toward the Communists, whose massive electorate overlaps their own. They denounce the party, its expanding cooperation with the Christian Democrats and, they allege, and insufficient concern with human rights.

Radical Party leader Marco Pannella made headlines with a flower-bearing visit to Communist Party headquarters that won him a slap from an irritated party guard.

The radicals held up the beginning of the new legislative session by insisting that their seats ought to be to the left of the Communists rather than the rights.

"Pannella is trying to carve out a politically space for his party with the seat of his pants," an old-time Communist, Giancario Pajetta, snapped at the time.

Excluded from much of the complex negotiating among Italy's six traditional or "constitutional" parties, the Radicals continue to rely on American-style protest sit-ins, hunger strikes, peace marches and civil disobedience - and on support from such "out" groups as feminists, homosexuals, convicts and conscientious objectors.

Some Italians though, criticize the Radicals' eight-point referendum, which would diminish police powers, repeal Fascist-period laws that limit freedom of expression and restructure the country's insane asylums, as potentially dangerous in a country as unstable as Italy.