President Barack Obama will nominate Mary Jo White, a partner at Debevoise & Plimpton and a former Southern District U.S. attorney, as the next chair of the U.S. Securities and Exchange Commission this afternoon, a White House official has confirmed.

White, now a white-collar defense lawyer, has been at Debevoise since 2002. Obama is expected to make the announcement at a 2:30 p.m. press conference at the White House.

White’s nomination would have to be confirmed by the Senate. She would replace Elisse Walter, a George W. Bush appointee who took over as chair in December when Mary Schapiro announced she would step down from the position.

White’s tenure in the U.S. Attorney’s Office was defined in part by high-profile terrorism cases.

Her office prosecuted Sheik Omar Abdel Rahman for seditious conspiracy in connection with a plot to blow up New York City landmarks, and it twice prosecuted Ramzi Yousef, first for his role in a plot to blow up U.S. airlines and then in connection to the 1993 bombing of the World Trade Center.

And it was White’s office that indicted Osama bin Laden and successfully prosecuted four men in the 1998 al-Qaida-led bombing of U.S. embassies in Kenya and Tanzania. Prosecutions are continuing to this day on a superseding indictment to the original indictment charging bin Laden, who was killed by U.S. forces in 2011.

But White, a 1993 Clinton appointee, also made aggressive efforts in targeting both street crime, through prosecutions of violent gangs in drug and gun cases, and white-collar crime and securities fraud cases.

During an interview on leaving the Southern District in 2002, White said she was proud that her office tripled the number of securities fraud indictments as part of what she called “an effort to get at the more systematic problems.”

White put pressure on major Wall Street firms, holding companies responsible for the actions of low-level employees or charging a company criminally. The office continues to prosecute scam artists and boiler-room operators in pump-and-dump stock schemes

But criminal charges were not the only way she leveraged the reputation and authority of the prosecutor’s office to effect change.

“I feel strongly as a philosophical matter that the way to go, most broadly, at white-collar crime is to look at what happens at major institutions,” she said. “You have to look very closely at corporate culture. Sometimes it has meant changes in the company, whether in its compliance program, or the company has agreed to having an outsider on its board of directors or agreed to enhance its internal controls.”