The embattled labor secretary, Alexander Acosta, on Wednesday defended the terms of a non-prosecution agreement he made 10 years ago with the financier Jeffrey Epstein, who at the time stood accused of sexually abusing underage girls.

Epstein was arrested at the weekend and charged anew in New York, on two counts of sex trafficking for allegedly abusing, manipulating and paying off dozens of young women and girls, some as young as 14. He pleaded not guilty.

The new charges against Epstein placed intense pressure on Acosta, who as a federal prosecutor in Florida in 2007 negotiated a secret deal with lawyers for Epstein that allowed Epstein to avoid serious prison time, protected Epstein’s co-conspirators and hid the existence of the agreement from dozens of alleged victims.

Earlier this year a federal judge ruled the deal illegal. But Acosta mounted an aggressive defense of the plea deal on Wednesday, arguing that the involvement of his office secured a greater penalty for Epstein than state officials otherwise would have managed.

“Without the work of our prosecutors, Epstein would have gotten away with just that state charge” and avoided jail time, Acosta said. “He was and is a sexual predator.”

Acosta’s characterization drew criticism from Barry E Krischer, the state attorney for Palm Beach county at the time of the Epstein case. “Mr Acosta’s recollection of this matter is completely wrong,” Krischer said in a statement to NBC News.

Krischer continued: “If Mr Acosta was truly concerned with the state’s case and felt he had to rescue the matter, he would have moved forward with the 53-page indictment his own office drafted. Instead, Mr Acosta brokered a secret plea deal that resulted in a Non-Prosecution Agreement in violation of the Crime Victim’s Rights Act.”

His assertion also contradicted an investigation by the Miami Herald over the past two years, which documented unusual contacts between Acosta’s office and Epstein’s defense, and quoted participants in the case as saying that Acosta’s office crumbled under pressure from Epstein’s attorneys.

“This press conference makes me respect Acosta even less than I did before,” tweeted Mimi Rocah, a former federal prosecutor in New York. “He’s trying to blame the state prosecutor, the line attorneys and paint himself as some hero who wanted to be sure Epstein got jail time.”

Barbara McQuade, a former US attorney from Michigan, told MSNBC: “I am normally very reluctant to second guess any prosecutor who had to deal with complicated facts … but I found several areas of [Acosta’s] statement today to be woefully inadequate, including this one where he portrays himself as the hero of the story.”

Acosta spoke as Democrats called for his resignation and the House oversight committee requested his testimony at a hearing examining the Epstein plea deal. Republican senators have likewise said they might investigate the deal.

Acosta denied that his relationship had soured with the White House chief of staff, Mick Mulvaney, who was reportedly encouraging Trump to cut Acosta loose.

Not true, said Acosta, asserting that Mulvaney had called him and told him media reports that Mulvaney opposed him “are, in his words, BS”

Asked why his office hid the plea deal with Epstein from alleged victims, Acosta said that a provision of the deal under which Epstein had to pay victim restitution could have been used by Epstein’s lawyers, if it were publicly known, to undermine the victims in court by raising questions about their motives.

“We live in a different world; today’s world does not allow some of the victim shaming that would have taken place at trial 12 years ago,” Acosta said.

That rationale was vehemently rejected by former prosecutors.

“Acosta’s suggestion that his obligation to protect victims was somehow different 12 years ago, because of changing societal attitudes, than it would be today is ridiculous,” tweeted the University of Alabama law professor Joyce Vance. “The more he defends his conduct the worse he sounds.”

Acosta would not say whether he would handle the case differently today.

A new alleged victim stepped forward on Wednesday, telling her story on NBC’s Today show.

Jennifer Araoz, 32, said Epstein raped her when she was 15. Her lawyers filed court papers on Wednesday as prelude to a lawsuit against Epstein. The papers said that beginning when Araoz was 14, she would give Epstein massages that would often lead to sex acts, the AP reported. Araoz said that after months of massages, Epstein, whose lawyers could not be reached for comment, forcibly raped her in 2002.

Pressed on whether he had called the news conference to placate Trump, Acosta said his relationship with the president was “outstanding” but acknowledged that he could be asked to resign at any time.

“I serve at the pleasure of the president,” Acosta said.