WASHINGTON – President Obama sent his strongest signal yet Thursday that he wants the government to get tougher with Wall Street, appointing a former prosecutor to head the Securities and Exchange Commission for the first time in the agency’s 79-year history.

Mary Jo White, former U.S. attorney in Manhattan, has an extensive record of prosecuting white-collar crime. White won convictions in the 1993 World Trade Center bombing and the 1998 terrorist attacks on two U.S. embassies in Africa, and put crime boss John Gotti away.

If confirmed, she will have the job of enforcing complicated regulations written in response to the worst financial crisis since the Depression.

“You don’t want to mess with Mary Jo,” the president said at the White House with White at his side. “As one former SEC chairman said, Mary Jo does not intimidate easily, and that’s important because she’s got a big job ahead of her.”

White would take over at the SEC from Elisse Walter, who has been interim chairwoman since Mary Schapiro resigned in December.

Obama also re-nominated Richard Cordray as head of the Consumer Financial Protection Bureau, created after the financial meltdown. The president used a recess appointment last year to circumvent Congress and install Cordray. That appointment expires at the end of this year.

White, 65, was the first woman ever to be named U.S. attorney in Manhattan, one of the most prestigious jobs in law enforcement.

Colleagues and politicians describe her as tough, no-nonsense and fiercely competitive. And she brings a wealth of legal bona fides to an agency that, critics say, failed to act aggressively to charge top individuals at the nation’s largest banks who may have contributed to the financial crisis.

Under Schapiro, the SEC brought civil charges with record penalties against Goldman Sachs, JPMorgan Chase and Citigroup, among others. But those settlements left top executives at the banks free from blame.

James Cox, a Duke University law professor and expert on the SEC, predicted White will push the SEC away from “being just a tollkeeper” that collects settlements and make it a forceful agency that brings meaningful sanctions against senior individuals.

“She has a high sense of the public purpose of the law,” Cox said. “You’ve got to change the culture of the SEC to the point where you’re willing to say, ‘We’re going to go after the individual.’ “