NEW YORK (CNN/Money) - Under fire for its plan to overhaul rules for overtime pay, the Bush administration has revised its proposal to protect overtime for police, firefighters and some white-collar employees earning up to $100,000 a year.

The Bush admin-istration has revised its proposals for rules governing overtime after critics said the plan would hurt millions of U.S. workers. CNN's Louise Schiavone reports. Play video (Real or Windows Media)

"Our intention is to clarify and modernize overtime pay rules," Labor Secretary Elaine Chao told reporters Tuesday. "There are a group of people who get overtime now, but are not guaranteed.

"The new rules also say first responders must also get overtime," she added.

First responders are classified as police, fire, medical technicians and other emergency personnel.

But critics were not assuaged by the administration's new proposal, which is set to go into effect in 120 days, according to the Department of Labor.

"The Bush administration simply is not trustworthy on this issue, and I am beyond skeptical about these so-called revisions," said Sen. Tom Harkin in a statement released Monday night.

Organized labor also voiced opposition before Chao's news conference and said it may challenge the regulations in court.

"The Bush administration staunchly opposed legislation which would preserve overtime pay for all workers," AFL-CIO president John Sweeney said in a statement Tuesday. The AFL-CIO is the nation's largest labor group with 13 million members.

But one labor law expert said the White House felt the political pressure and improved on the original proposals released a little more than a year ago.

"This is clearly a compromise position," said Camille Olson, a partner and labor law specialist with Chicago-based law firm Seyfarth Shaw. "In the end, I'd be surprise if labor did have concerns."

The department proposed new rules on overtime pay in March of last year, but revised them amid criticism from Democrats and some Republicans in Congress.

Backers contend the revised regulations will update old rules, reduce the amount of class-action lawsuits and cover more workers.

"There are more class-action complaints against companies over overtime pay than there are about harassment," Secretary Chao added, noting the new rules attempt to reduce confusion over what workers are eligible for overtime pay.

Seyfarth Shaw's Olson said class-action suits over wages have become very prevalent and often take years to complete.

"Because they are class-action, they take an enormous amount of time to figure out who is and isn't eligible. The new regulations provide some more definitiveness," she said, noting that many cases emerge from the retail sector.

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More than 50 years ago, the Fair Labor Standards Act created the 40-hour work week by guaranteeing overtime pay for millions of workers for each additional hour on the job. Administrative, professional and executive employees were exempted.

Last year, the Department proposed allowing more employees to be reclassified as administrators, professionals or executives, provided they met certain criteria.

Under that proposal, employees earning more than $65,000 a year would not be eligible for overtime if they met one or more of the criteria.

The revised regulation raises the figure to $100,000. Yet opponents still voice worries that millions of people earning less than that would still lose overtime protection.