WASHINGTON — With a few confirmation victories in his pocket, President Obama decided Monday to press ahead with another cabinet nominee in defiance of Republican opposition as he tapped an assertive civil rights regulator to be his next labor secretary.

Mr. Obama’s nomination of Thomas E. Perez, who has racked up record discrimination and housing claims as head of the Civil Rights Division at the Justice Department, generated criticism from some Senate Republicans who called him a divisive and political choice. But after pushing through other disputed nominees, most notably Chuck Hagel, the defense secretary, Mr. Obama calculated he could win another fight.

It might even be a fight that he wants to have. Mr. Perez has been aggressive in pursuing cases in areas that have been priorities for the president, particularly voting rights and discrimination against Hispanics. Mr. Obama brushed aside a critical report about political divisions in a section under Mr. Perez to advance a candidate who drew praise from liberals and labor leaders and would be the only Hispanic in the cabinet.

In a ceremony in the East Room of the White House on Monday, Mr. Obama presented Mr. Perez as an immigration success story. “Like so many Americans, Tom knows what it’s like to climb the ladder of opportunity,” Mr. Obama said. “He’s the son of Dominican immigrants. He helped pay his way through college as a garbage collector and working at a warehouse. He went on to become the first lawyer in his family.”