Cleveland voters put themselves at an ideological crossroads today as Republican Lt. Gov. George V. Voinovich and self-styled populist Mayor Dennis J. Kucinich topped a field of five candidates in mayoral balloting.

With 638 of 645 precincts reporting, Voinovich outdistanced Kucinich, 47,324 votes to 36,189.

Trailing were City Council Majority Leader Basil M. Russo, with 21,623 votes, and State Sen. Charles Butz, with 19,202.

The two top vote-getters will square off in the Nov. 6 general election.

Until now Kucinich has operated outside the Democratic Party during 11 years in politics. But tonight he embraced it.

"We'll be carrying the banner of the Democratic Party" in November, he declared as the vote count neared an end. "The November election will be the people against fatcats, the Democrats against the Republicans."

There was a light voter turnout despite fair weather and the national attention focused on this election, which put Kucinich, one of the nation's youngest big-city mayors, in an uphill battle for reelection.

With Voinovich and Kucinich vying to be mayor, voters now must decide if the remedy for Cleveland's municipal problems is Kucinich's so-called urban populism or Voinovich's conservatism.

Kucinich has maintained a hard-line stance against the city's establishemnt. Voinovich, though not a favorite of this city's corporate elite, is expected to take a more moderate stance toward business.

Kucinich had portrayed Voinovich as a pawn of what he called business fat-cats. The mayor charged that Voinovich laundered almost half of his $140,000 in campaign contributions through the Republican Party in what Kucinich termed a Watergate-style maneuver.

Voinovich attacked Kucinich on his handling of basic city services. He said that while Kucinich had inherited a severe financial problem, the mayor had done nothing to improve it as Cleveland became the first big city to default since the Depression.

"The smartest thing that Dennis can do now is to stop attacking me and start talking about what he's going to do to improve the city's problems," Voinovich said tonight as it became apparent that he was the frontrunner. He immediately called for bipartisan support in November's general election. $5However, Timothy Hagan, chairman of the Cuyahoga County Democratic Party, said, "There's no way in hell we would support a Republican against Kucinich. George Voinovich is a Dennis Kucinich in a Brooks Brothers suit."

Republican Party Chairman Robert E. Hughes said, "There was only one issue in this election: Dennis Kucinich, his personality and his style.

"The people of Cleveland voted for hope. They hope things will get better. Dennis has had high visibility for two years and things are worse. They are tired of confrontation politics."

Voinovich was elected lieutenant governor last year on a ticket with Gov. James A. Rhodes. Rhodes put Voinovich on the ticket to increase his strength in Cuyahoga County, where his gubernatorial opponent, Richard F. Celeste, a Democrat, was favored.

Kuciniich was elected to the $50,000-a-year mayor's job in 1977 by 3,000 botes out of 180,000 cast. He survived a recall attempt in August 1978 by 236 votes.