President Barack Obama on Monday nominated Thomas E. Perez, an assistant attorney general at the Justice Department, as his next Labor secretary, saying he has “spent a career as a consensus builder.”

“Like so many Americans, Tom knows what it’s like to climb the ladder of opportunity,” Obama said. “He helped pay his way through college as a garbage collector and working at a warehouse.”

The president called Perez “the right person for this job” and he urged the Senate to “confirm him as quickly as possible.” He said Perez will be “an integral part of our overall economic team” and will play a role in the administration’s effort to “build an immigration system that works for every employee, every family and every business.”

The decision is likely to set in motion another partisan debate over one of Obama’s second-term Cabinet appointees, as Perez’s lengthy record as the administration’s chief enforcer of civil rights laws met with some initial Republican questioning last week, even before his nomination became official.

“This is an unfortunate and needlessly divisive nomination,” Sen. Jeff Sessions, R-Ala., said in a statement Monday. “Mr. Perez has aggressively sought ways to allow the hiring of more illegal workers. Mr. Perez has also had a controversial tenure at the Department of Justice where he has demonstrated a fundamentally political approach to the law.”

According to Sessions, Perez served as president of the board of Casa de Maryland, which the senator called “a fringe advocacy group that has instructed illegal immigrants on how to escape detection, and also promoted illegal labor sites and driver’s licenses for illegal immigrants.” As a Montgomery County councilman in 2003, “Mr. Perez advocated for allowing illegal immigrants to be able to use foreign identification, known as matricula cards, in place of a valid U.S.-issued ID to work and receive public services,” Sessions said.

Only Latino

Perez is of Dominican descent and, if confirmed to succeed Hilda L. Solis, who stepped down in January, he would be the only Latino in Obama’s second-term Cabinet. He previously served as Maryland’s Labor secretary, in the Office of Civil Rights at the Health and Human Services Department and as a special counsel to the late Sen. Edward M. Kennedy, D-Mass.

Although the Senate confirmed Perez as head of the Justice Department’s Civil Rights Division on a bipartisan 72-22 vote in October 2009, he has sparked partisan debate on several fronts since then.

Perez succeeded in blocking Republican-backed voting laws in South Carolina and Texas that his division deemed racially discriminatory. He pressed racial profiling charges against Joe Arpaio, the Republican sheriff of Maricopa County, Ariz., who is among the most divisive figures in the national immigration debate. His handling of a legal agreement with the city of St. Paul, Minn., in a lending discrimination case has drawn condemnation from Sen. Charles E. Grassley of Iowa, the top Republican on the Judiciary Committee, who has called it a “quid pro quo” and a “shady deal.”

Senate criticism of Perez so far has come primarily from Grassley and the Judiciary Committee, which oversees the Justice Department and is seen as one of the more-partisan panels in the chamber. Perez’s nomination to the Labor Department will not come before the Judiciary Committee, however. It will come before the Health, Education, Labor and Pensions Committee, where Sen. Lamar Alexander of Tennessee is the top Republican.

Alexander declined earlier CQ Roll Call requests to discuss Perez until the nomination was made official. But the White House’s announcement is certain to elicit swift responses, as both Democrats and Republicans gear up for what could be another contentious nomination fight.

Steven T. Dennis contributed to this report.