When the stakes could not be higher, the U.S. government looks to Kenneth Feinberg to untangle and defuse its most politically and emotionally challenging disputes.

Feinberg has doled out hundreds of millions of dollars to victims of the September11, 2001 attacks, Virginia Tech shootings and Vietnam-era Agent Orange poisonings.

As special master for those cases, he has overseen funds for survivors and relatives of those who died, while mostly skirting controversy.

Feinberg, 63, may face his toughest challenge yet as the Obama administration's pay czar, exerting authority over the highest-paid employees at massive companies bailed out by U.S. taxpayers.

It's certainly intense and it's been unbelievably long hours, said Camille Biros, business manager at Feinberg's law firm Feinberg Rozen LLP.

She has been working closely with Feinberg, who declined to comment for this article, and the seven bailed-out firms who must submit pay plans to the Treasury Department.

Feinberg splits his time between a somewhat cramped office at Treasury and a meticulously maintained office at his private practice across the street, arriving at 6 a.m. and not leaving until 7 p.m. when he goes home to take more calls, Biros said.

And that is before Friday's deadline for several companies that received taxpayer bailouts to submit their plans for compensating their 25 highest-paid employees. Feinberg is receiving no compensation in his role.

From the day he was appointed in June, Biros said, Feinberg has been meeting with the seven companies -- Citigroup Inc (C.N), American International Group Inc (AIG.N), Bank of America Corp (BAC.N), Chrysler Financial CCMLPF.UL, Chrysler Group LLC, General Motors Co GM.UL and GMAC Inc.

They were asking his advice about what might be acceptable and what might not be, said Biros, who has worked with Feinberg for 30 years. He listened and hopefully provided that guidance in terms of pay scale.

Many believe Feinberg will be squeezed between public fury over outsized bonuses on one side and what is best for companies trying to compete and retain talent in a marketplace that demands million-dollar salaries on the other.

If Feinberg rules that big compensation packages are mostly fair, lawmakers may assail him as the tool of corporate interests. If he tries to strike down salaries, boards and shareholders may blame him for chasing away the rainmakers.

The whole idea of a pay czar was a really bad idea, said Charles Elson, the director of the Weinberg Center for Corporate Governance at the University of Delaware. He is in a no-win situation.

'PERSUASIVE ABILITY'

Feinberg, the son of a tire merchant, has described himself as an average student at rough-and-tumble Brockton High School in Massachusetts.

But he excelled in college, graduating with honors from the University of Massachusetts and becoming the first student to deliver the commencement address at graduation.

After college, Feinberg entertained the idea of pursuing an acting career. His father told him to play Hamlet in front of juries instead. He attended law school at New York University.

He still speaks like a Brockton street brawler, dropping his R's, but has cultivated a taste for opera. He listens to it throughout the work day, and is president of the Washington National Opera.

Arlin Adams, a former U.S. appeals court judge from Philadelphia and longtime colleague, said Feinberg has a knack for calm negotiations.

He has to depend in a large part on his ability to persuade, Adams said. But he does have a great deal of persuasive ability.

Mary Vail Ware, director of Virginia's Criminal Injuries Compensation Fund, said Feinberg adeptly handled his responsibilities with the September 11th victim's fund and the Hokie Spirit Memorial Fund for victims of the 2007 shootings at Virginia Tech.

Ware, who worked with Feinberg on both, said the role of compensation czar will put Feinberg in some critics' crosshairs, but that it will be considerably less taxing than the personal tragedies that dominated his prior jobs.

When I heard he was doing that I did get a little chuckle because compared to the other things he has done, this is cake, Ware said.

Biros said Feinberg's enthusiasm to take on unenviable tasks for no pay is not new. She said he is simply interested in public service. We never know from one day to the next what project we're going to get involved with, she said.