Backed by the political steamroller built by his mentor, the late Mayor Richard J. Daley, Michael A. Bilandic won a Chicago Democratic mayoral primary today considered tantamount to victory in the general election.

Bilandic has been Chicago's acting mayor since shortly after Daley died Dec. 20, ending a 21-year reign as Chicago's boss.

The 54-year-old Bilandic, a corporation lawyer, overwhelmed five opponents behind the blitzkrieg charge of Chicago's mighty Regular Democratic Organization.

Bilandic's victory became apparent when he ran away from his chief opponent, Alderman Roman C. Pucinski, in the Southwest Side Polish wards that Pucinski had counted upon.

With 180 out of 3,085 precincts counted, Bilandic led Pucinski, 22,872 to 15,839. State Sen. Harold Washington, a black candidate counting on black support was third with 2,003 votes and charged "massive vote fraud." The other Democrats Ellis E. Reid, a black attorney; lawyer Anthony R. Martin-Trigona; and former U.S. attorney Edward Hanrahan.

Dennis H. Block, 29, Chicago's only Republican Alderman, easily won nomination over three contenders for the GOp nomination to run in the June 7 general election.

Chicago has not elected a Republican mayor in 49 years.

Before the voting began, officials predicted a turnout of about 41 per cent, or 666,000, of the 1.6 million registered voters.

In 1975 when Daley threw aside a challenge by a vigourous independent, about 37 per cent of the votors cast ballots.

Bilandic, 55, chosen acting mayor by the City Council after Daley's death in December, is a soft-spoken bachelor from Daley's own 11th Ward who for years toiled hard behind the scenes for Daley.

He was persuaded by Daley to run for his first public office in 1968 when he was elected aldeman from the ward that has produced every Chicago mayor since Ed Kelly took office 44 years ago.

He became a confidant of Daley and the choice to succeed him among regular party Democrats, including State Sen. Richard Daley, the late mayor's son who has emerged as a power broker.

When Bilandic assumed the acting mayor's post, he pledged he would not be a candidate in the special election. His reversal angered his opponents, including Pucinksi who argued that a Bilandic administration would mean more "politics-as-usual."

But the candidates rarely talked about the flight of industry from the city, mass transportation, the quality of schools and racial integration.

Bilandic chose to run a campaign in the style Daley perfected. He appeared at charitable dinners, ribbon-cuttings and ceremonials, portraying himself as a friend to business and a successful labor mediator as well.

Pucinski emphasized unemployment and charged unfair campaign tactics by Bilandic, saying his campaign workers and supporters were threatened by landlords or city inspectors.

He hinged his hopes on a core of ethnic support, specifically from Poles like himself who make up the single largest Polish population in any city except Warsaw.