NEWARK — Hillary Clinton on Wednesday seized upon revelations about Trump University, the for-profit institution started by Donald J. Trump, calling him a “fraud” who wants to rip off the country he is running to lead.

In the first minutes of her speech at a rally here, Mrs. Clinton brought up newly released testimony by former employees of what she called “the so-called Trump University,” telling the crowd, “You can’t make this up.”

The testimony, released on Tuesday, portrayed Trump University as an unscrupulous business that used high-pressure sales tactics and deceptive marketing to lure thousands of people to enroll in classes. In many cases, the employees said, customers were persuaded to purchase classes they could not afford, by opening credit cards or borrowing the money.

Speaking at the Newark campus of Rutgers University, Mrs. Clinton told the crowd that employees had testified “that Trump U. was a fraudulent scheme where Donald Trump enriched himself at the expense of hard-working people.” She said that Mr. Trump and those who worked for him “took advantage of vulnerable Americans.”