Republicans have been bracing for a storm ever since President Obama tapped Thomas Perez, the liberal activist head of the Justice Department's civil rights division, to replace Hilda Solis as Labor secretary.

Labeling Perez a radical, polarizing figure, Republicans held up his nomination for four months, allowing it to move forward only on July 18 as part of a deal to prevent Senate Democrats from going nuclear and changing the chamber's voting rules.

Now employers and their GOP allies in Congress worry it's payback time.

During Solis' tenure at Labor, the department focused most of its energy on writing and implementing Obamacare while other regulatory work piled up.

Now, free-enterprise advocates are preparing for their worst nightmare -- a flood of onerous regulations at a delicate time in the country's economic recovery from a man who Republicans know is smart and aggressive.

"Tom Perez is more than just a left-wing ideologue -- he's a left-wing ideologue who appears perfectly willing to bend the rules to achieve his ends," Senate Minority Leader Mitch McConnell said after voting against his confirmation.

Republicans also privately worry that Obama's appointment of a Hispanic to the most ideological Cabinet post will make their public clashes with him over policy affirm an anti-Hispanic perception of the GOP.

More broadly, Perez's resume has all the hallmarks of a perfect poster child for the Democratic Party -- and nothing reassuring to Republicans.

The son of first-generation Dominican immigrants -- his father received his citizenship after serving in the U.S. Army -- Perez, 51, earned degrees from Brown University and Harvard law school before going to work the first time for the civil rights division at Justice when Janet Reno was attorney general. He left to join Sen. Ted Kennedy's legislative team until 1998 when President Clinton tapped him to be director of the Office for Civil Rights at Health and Human Services.

Gov. Martin O'Malley, Maryland's liberal Democratic governor, later appointed Perez to run the state's Department of Labor in 2007. While there, he helped implement the country's first statewide living-wage law and is credited with giving new life to what many considered a moribund agency.

Luke Clippinger, a member of the Maryland House of Delegates who ran Perez's failed 2006 bid for state attorney general, said GOP attempts to demonize Perez are misguided. Perez is a consensus-builder, he says, and his commitment to safeguarding employees makes for a more productive workplace.

Another longtime colleague, Mara Youdelman, is the managing attorney of the Washington office of the National Health Law Program, a public interest law firm aimed at improving health care for the minorities and the poor.

She partnered with Perez when he was teaching law school at the University of Maryland in the early 2000s to help place students with organizations like hers, and marvels over his unflinching work on behalf of the underprivileged.

"He has demonstrated a lifelong commitment to making sure the underserved have a voice and have advocates," she said.

Republicans acknowledge Perez's good intentions and dedication to championing the causes he believes in. They simply disagree with his interpretation of the nation's laws and the cases he prioritizes.

At Justice, Perez took on photo identification laws in South Carolina, helped with a discrimination suit against the New York City Fire Department because too few minorities passed the department's entry exams and filed suit against a school district in New York for failing to protect a 14-year-old boy who dressed in drag from being harassed.

Last year, Perez sued Arizona's Sheriff Joe Arpaio for profiling illegal immigrants and, following Obama's lead, waded into the Trayvon Martin case by investigating accusations that shooter George Zimmerman was motivated by racial bias - a probe Attorney General Eric Holder renewed after Zimmerman's not-guilty verdict.

Among a litany of complaints, Republicans say a Justice inspector general report found that Perez failed to testify truthfully before the U.S. Commission on Civil Rights three years ago regarding the 2008 voter intimidation case involving the New Black Panther Party.

During his confirmation hearings, Perez highlighted his 13 years of work at DOJ under four presidents - Ronald Reagan, George H.W. Bush, Bill Clinton and Barack Obama.

He also tried to appeal to areas of bipartisan agreement, noting that he had increased by 40 percent the number of human trafficking cases that Justice prosecuted and recovered $50 million for service members whose homes were improperly foreclosed on while deployed.

Those actions failed to generate even one Republican vote for his confirmation.

Clippinger said Republicans are simply nervous that Perez will robustly enforce labor laws - a criticism he found "remarkable."

"People should expect [government officials] to do their jobs and do them with vigor, and I think he will definitely do that as secretary."

That's exactly what Republicans are worried about.