SIOUX CITY, IOWA, OCT. 2 -- A group of angry Democrats tonight disrupted a rally for Massachusetts Gov. Michael S. Dukakis, loudly complaining about the role his campaign played in the downfall of the presidential candidacy of Sen. Joseph R. Biden Jr. (D-Del.).

The outburst came at the end of a grueling, six-city campaign swing in a hot, crowded union hall as Dukakis apologized that his top aides secretly circulated a videotape showing Biden plagiarizing a British politician.

A prim, gray-haired woman interrupted Dukakis's speech by asking why he took "so long" to accept the resignation of his campaign manager, John Sasso, who ordered the videotapes prepared.

"Timing it to come up during the Bork hearings was a horrible thing to do to the Democrats," Cecilia Flanagan of Sioux City shouted.

"Why do you want to hang a man who walked on the wrong side of the street?" an angry man asked.

"I think Dick Gephardt deserves an apology," said a woman of Rep. Richard A. Gephardt (D-Mo.), whose campaign had been suspected of leaking the "attack video" to reporters.

A number of people in the crowd jumped to Dukakis's defense. "I think it's time to get on with the campaign," declared a man in the second row. "We came to listen to the governor, not you," someone else shouted.

The outburst was expected. Dukakis reacted to it calmly and unflinchingly as an irate Biden supporter lectured him.

Sioux City was the biggest center of Biden support in Iowa, and his former supporters have been complaining for days about what befell the Delaware Democrat.

"He {Dukakis} wants to face the music, and in my opinion the music is 'Taps,' " Biden supporter Tim Bottaro, who orchestrated tonight's disruption, warned on Thursday.

Dukakis was 40 minutes late in arriving for the rally at a communication workers' union hall. The deep division was evident as the governor entered the room. Two-thirds of the crowd of about 200 gave him a standing ovation; the rest sat silently as he pushed his way through the elbow-to-elbow crowd.

State Rep. Steve Hansen said the crowd could have been more unruly had many Biden supporters not refused to attend the rally. "Several told me they didn't want to dignify him {Dukakis} with their presence. We have some bitter people here," he said.

The rally was the only sign of open discontent a tired and contrite Dukakis encountered today as he moved across the rolling Iowa prairie, apolgizing for the role of his campaign in Biden's downfall.

Dukakis said he was "very saddened and apologetic about what happened" and pledged "to do everything I can to make sure that this is the last time it happens."

Voters in the small western Iowa communities of Ida Grove, Sac City, Cherokee and Onawa, where Dukakis spent much of his day, appeared to accept that message.

In the farm community of Onawa, for example, Isabel Carlson, 66, said it was unfair "to crucify" Dukakis for the actions of his aides.

"We {Democrats} have a tendency to do that and none of us is lily white," she said. "I think we should take that under consideration. Otherwise we're not going to have anyone good running."

"There is no place in American politics for people hurting other people," he said during stops en route here.

It was a bright, chilly day in the middle of the harvest season, and tonight the weather forecast warned of fall's first frost.

Today was Dukakis's first extended political swing since his campaign manager, Sasso, and his political director, Paul Tully, resigned Wednesday after Dukakis acknowledged Sasso had given reporters a videotape that helped destroy Biden's candidacy.

Tom Fiox, who is the Woodbury County Democratic chairman, and other leading Democrats here complained that Dukakis "condoned dirty tricks" by not accepting Sasso's resignation until almost 24 hours after Sasso had informed the governor of his involvement in the affair. "That sent a message that anything goes as long as you're winning," Fiox said.

"The governor owes us and the Democratic Party an apology. What his campaign did was despicable," he said. "We don't condone that kind of campaign in Iowa."

The video, showing Biden liberally borrowing, without attribution, the words of British Labor Party leader Neil Kinnock, was prepared under Sasso's direction and sent out with the knowledge of Tully and at least one other Dukakis aide, field director Jack Corrigan.