WASHINGTON — President Obama said Sunday that he would nominate Richard Cordray, the former attorney general of Ohio, to lead the new Consumer Financial Protection Bureau, passing over Elizabeth Warren, the Harvard law professor who was the driving force behind the agency’s creation.

Mr. Cordray came to national attention for his aggressive investigations of mortgage foreclosure practices while he was attorney general. He is already an employee of the watchdog agency, which starts formal operations on Thursday, as the leader of its enforcement division.

“Richard Cordray has spent his career advocating for middle-class families, from his tenure as Ohio’s attorney general to his most recent role as heading up the enforcement division at the C.F.P.B. and looking out for ordinary people in our financial system,” Mr. Obama said in a written statement. He is expected to formally announce the nomination on Monday.

Congress created the bureau a year ago this week with the enactment of the Dodd-Frank law, which overhauled financial regulations after the credit crisis. The bureau, a centerpiece of the sweeping new law, has since emerged as one of the thorniest topics in Washington and on Wall Street.