David Robbins, a dark horse candidate for Montgomery County executive, broke the tension at a public meeting last night when he stole a line from actor-politician Clint Eastwood, saying: "I go into this election never having run for public office before but supremely confident of the outcome."

Robbins could not have delivered his line to a more appreciative audience -- the 100 active Democrats who turned out in Rockville to hear David Scull, Sidney Kramer and Robbins explain with equal confidence why each deserves the party's nomination to be the next executive of Montgomery's government.

The candidates' two-hour debate -- their first together, with exactly five months to go before the Democratic primary election -- was dominated by a running and sometimes caustic exchange between Kramer and Scull, with Robbins needling the two front-runners from the sidelines.

All three agreed on the need to ease traffic congestion in the booming suburb, but parted ways on how best to accomplish that goal. They also called for improvements in local education, such as pay equity for teachers, and pledged to disclose their income tax returns and real-estate holdings in the county.

Kramer, Robbins and Scull disagreed only mildly about what the county government, with its $1 billion-a-year budget, should do for its taxpayers, but did offer local party leaders quite different styles.

The audience was particularly important to all three candidates because it was made up primarily of Democratic precinct officials, the backbone of a local party whose members outnumber Republicans on county voter registration rolls by a roughly 2-to-1 margin. Republicans Albert Ceccone and Edward J. Gannon are competing for the Republican nomination to run against the winner of the Democrats' September primary.

Scull, at 42 the youngest of the Democratic candidates, stressed his career as a County Council member, proclaiming himself heir to a family tradition that "revered public service as a high calling." He sought to deflect widespread criticism of the all-Democratic but faction-torn County Council by calling for "a fresh start" and promising to mend fences with party activists if elected.

Robbins, the 51-year-old director of the county recreation department, warmed to the crowd with occasional one-liners and attempted to portray himself as a candidate beholden to no wing of the party.

"It is time to encourage new leadership . . . not saddled by intraparty divisiveness and not compromised by special interests," Robbins said in apparent references to Scull and Kramer, respectively.

Kramer, 60, who is retiring from the state Senate to run for the executive's job, has been hounded for weeks by Scull's attacks on the large business contributions he has received. Kramer has challenged Scull to reveal his own list of campaign contributors, but Scull has not done so.

Kramer accused Scull and his council colleagues of failing to implement fully a 1973 law designed to ensure adequate roads and schools. "We're pointing the finger of blame on the development community, instead of the County Council where it properly belongs," Kramer said.

The sharpest exchange of the night came when Scull criticized Kramer for supporting in the General Assembly a bill that would have threatened Montgomery's policy of reusing former school buildings as housing for elderly citizens, among other uses. Scull said Kramer wanted to repeal the policy "back to the Stone Age," while Kramer said some new uses for schools "subvert the zoning process."

Members of the House of Delegates from Montgomery County killed the bill this winter.