When Mr. Trump told him of the undocumented workers, Mr. Sullivan said he responded: ''I think you are nuts. You are here negotiating a lease in Atlantic City for a casino license and you are telling me you have got illegal employees on the job.''

Mr. Trump testified that Kaszycki & Sons fell behind, and that he only vaguely recalled complaints of payment problems. He said he did not remember threats against an employee.

He also said that Mr. Sullivan was a peripheral adviser.

Using the Name John Baron

Asked whether he knew about undocumented workers, Mr. Trump said, ''I really still don't know that there were illegal aliens.''

In earlier testimony to show the Trump organization knew about the undocumented workers, John Szabo, an immigration lawyer who represented them, said someone who said his name was Mr. Baron telephoned on behalf of the Trump organization in 1980 and threatened to sue him if he did not drop the workers' claims of back payments.

Mr. Trump acknowledged yesterday that he and one of his executives have used the name John Baron in some of their business dealings. He did not explain. And he was not asked about Mr. Szabo's allegation.

Mr. Szabo said his clients told him that to complete the demolition, they worked seven days a week, 12 hours a day. During a transit strike, some of them walked from the Greenpoint section of Brooklyn to the Fifth Avenue job site, he said. Many of them were never paid all that was owed them, he said.

A Tight Deadline and Concern

Mr. Trump acknowledged that his deadline was tight, and that he became greatly concerned when Kaszycki & Sons fell behind. He said that he considered pulling them off the job, but realized it would cost him months. So he decided to put more money into their contract so they would have enough to move faster.