The three front-runners in the contest for the Republican lieutenant governor's nomination in Virginia sharpened the battle lines in their campaigns last night during their first debate in Northern Virginia.

Richard A. Viguerie, a pioneer in direct-mail campaigning for conservative causes and candidates, leaned heavily on his role in national politics to boost his first campaign for a state office and to separate his candidacy from his opponents.

Former Virginia attorney general J. Marshall Coleman of McLean and state Sen. John Chichester of Fredericksburg targeted more traditional issues.

Coleman hammered at problems of mismanagement in the state's prisons, which he blamed on a "lack of leadership" by the present administration of Democrat Charles S. Robb. Robb beat Coleman for the governorship four years ago.

Chichester, in his first statewide race, said he would concentrate his energies on attracting new business to the state.

Two other candidates in the five-man race -- State Del. A.R. "Pete" Geisen of Augusta County and Washington lobbyist Maurice Dawkins of Springfield -- did not participate in the debate at the Lyon Village Community Center, which was sponsored by the Arlington Area Young Republicans.

Although the candidates shied away from attacking each other during the 80-minute debate, they were quick to seize on issues that separate them in a campaign that has been overshadowed by a fierce race for the Republican gubernatorial nomination.

Viguerie, who arrived 45 minutes late because of a fund-raiser for him at his McLean home, tried to deflect criticism of his entry into statewide politics. "I've been on the cutting edge of the issues of concern to the people of Virginia," he said. "No one has done more across the country -- I hate to be immodest -- to elect Republicans than myself." Frequently during questioning before the audience of about 100, Viguerie turned questions on local issues into answers addressing national concerns.

In contrast, Coleman and Chichester dwelled on their experience within state government. "The crisis and chaos in the state's prisons has been due to a lack of leadership," charged Coleman, continuing his criticism of Robb on the issue that began with the escape of six death-row inmates from the state's Mecklenburg Correctional Center last spring.

"I have chosen economic development as an issue," said Chichester who said he would spend much of his time as lieutenant governor traveling the state and trying to lure new industry into Virginia.

And each of the candidates said that he strongly opposed abortion.