"They're going to be hard hit, because tips, commissions, overtime and all those things, along with hours, are going to be cut," as the economy struggles, Allegretto said.
The effect is hard to quantify because the Labor Department doesn't track pay for this group of workers as a whole, she said. But for many, the pain has been quick and deep.
Until last year, 58-year-old Michael Klein made about $125,000 a year selling Hummer SUVs at a dealership in Concord, Calif., near San Francisco. With 20 years' experience, Klein was accustomed to moving 15 to 25 vehicles a month. Then gas prices soared and loans dried up. So did his client base.
Now Klein works seven days a week, 12 hours a day, just to sell eight cars a month. His income has shrunk by more than half.
Normally, he's paid solely through commissions. But when business suffers, his dealership pays a subsidy to make sure a salesperson's pay for a month is no less than $1,500. Recently, Klein has sold so few cars that for the first time he's qualified for the subsidy.
Klein, who's divorced with adult children, can afford about two-thirds of his mortgage payment. He's trying to re-negotiate his loan. In the meantime, his bank has sent him notices of late and insufficient payments.
"I said: 'If you can work with me, fine. If not, here's the house,"' he said. "They don't want the house."
Klein has quit traveling to see his daughter and grandchild in Las Vegas. He's stopped seeing movies and eating out.
But he clings to the spirit of a salesman. His new pitch to customers is that Hummers and other SUVs can be just as economical as compact cars: They fit more people.
While earnings for commission-based workers drop quickly, those paid in wages will endure a somewhat slower pay decline this year, said Ken Abosch, head of the North American practice for Hewitt Associates compensation consultants.
A Hewitt survey of 640 companies found they planned to raise hourly wages 2.5% this year. That's the smallest raise since 1976. The companies said executive pay increases would drop from 3.8% to 2.2% in 2009.
But for millions of workers, the biggest problem is a shortage of hours available. Last month, the average work week fell to 33.3 hours. That's the lowest level since the Labor Department began tracking the figure in 1964.
More than 7.8 million U.S. employees are working part time because they can't find full-time work, according to department figures, the largest number recorded — and a 65% increase from 12 months ago.
For workers like Richard Thomas, that means getting by without the health insurance and other benefits afforded to many full time employees.
Thomas worked as a full-time truck driver until last summer, when business slowed. He was paid by the mile. As orders slowed, he sat idle for days at a time. He thought steady work back home in St. Louis would help boost his income. But he could find only a part-time job as a school-bus driver.
Thomas, 36, says he usually gets 25 hours a week of work. On good days, he finds odd jobs, like fueling up buses, to boost his pay. Lucrative gigs, like driving field trips, are handed out based on seniority, and Thomas said he rarely gets them.
The job is helping him pay rent and bills. Even without a family to support, there's no money left for frills. A typical night of entertainment consists of watching movies on his laptop. He spends much of his spare time hunting for work.
Because they're working, part time employees like Thomas aren't eligible for unemployment benefits or welfare. But he said he doesn't let that bother him.
"I would rather get one of those good jobs myself," he said.