Holland, Mich. - This stretch of the Rust Belt might seem like an easy place to find factory workers.

Unemployment hovers above 9 percent. Foreign competition has thrown many out of work. It is a platitude that this industrial hub, like the country itself, needs more manufacturing work.

But as the 2012 presidential candidates roam the state offering ways to "bring the jobs back," many manufacturers say that, in fact, the jobs are already here.

What's missing are the skilled workers needed to fill them.

A metal parts factory here has been searching since the fall for a machinist, an assembly team leader and a die-setter. Another plant is offering referral bonuses for a welder. And a company that makes molds for automakers has been trying for seven months to fill four spots on the second shift.

"Our guys have been working 60 to 70 hours a week, and they're dead. They're gone," said Corey Carolla, vice president of operations at Mach Mold, a 40-man shop in Benton Harbor, Mich. "We need more people. The trouble is finding them."

Through a combination of overseas competition and productivity gains, the United States has lost nearly 4 million manufacturing jobs in the past 10 years. But many manufacturers say the losses have not yielded a surplus of skilled factory workers.

Instead, as automation has transformed factories and altered the skills needed to operate and maintain factory equipment, the laid-off workers, who may be familiar with the old-fashioned presses and lathes, are often unqualified to run the new.

Compounding the problem is a demographic wave. At some factories, much of the workforce consists of baby boomers who are nearing retirement. Many of the younger workers who might have taken their place have avoided the manufacturing sector because of the volatility and stigma of factory work, as well as perceptions that U.S. manufacturing is a "dying industry."

"Politicians make it sound like there's a line out front of workers with a big sign saying, 'No more jobs,' " Matt Tyler, chief executive of a precision metal company in New Troy, Mich. "Nothing could be further from the truth."

The shortage of skilled workers was noted before the recession, but the phenomenon has become more acute with the recent recovery.

Just this week, Tyler said, when a fracking company asked him to make pieces for pipes, his chief worry was whether he could find six new operators to do the work.

"This was never a problem I thought we'd be having," he said.

The frustrations are shared across the country.

A recent report by Deloitte for the Manufacturing Institute, based on a survey of manufacturers, found that as many as 600,000 jobs are going unfilled. By comparison, the unemployed in the United States number 12.8 million, according to the Bureau of Labor Statistics.

"High unemployment is not making it easier to fill positions, particularly in the areas of skilled production and production support," the Deloitte report found.

Similarly, the Bureau of Labor Statistics reported that although fewer machinists would be employed in the future, job opportunities "should continue to be good" because many young people with the right aptitudes were preferring other fields.

"It used to be that a factory owner would say, 'I need 20 guys,' and pull them right off the street," P.J. Thompson, president of Trans-Matic, a metal-parts manufacturer. "Now it's: 'I need 20 guys with very specialized technical skills.' There's a mismatch."

Driving this shortage is the way that automation is transforming U.S. manufacturing.

Much of the demand for skilled workers arises because the automated factories demand workers who can operate, program and maintain the new computerized equipment. Many of those who have been laid off can operate only the old-fashioned manual machines.

The old lathes and mills were operated by hand and turned out pieces one by one. The new ones, as big as minivans and arrayed with screens and buttons, must be programmed with codes that sometimes look arcane.

The computer numerically controlled, or CNC, machines can cost hundreds of thousands of dollars. Once they are programmed, they churn out piece after piece unattended.

One day last week, for example, Greg Rowles, 27, a former tow truck driver who is now a CNC programmer, was working on a machine to shape a metal part at the Vickers Engineering plant in New Troy. He took some classes at the local community college. The codes he typed in looked like this:

G54G90G0B0

M7;

G4X3.;

G81Z-.829R.1F28.;

The last line, he said, tells the machine to take a tool and drill .829 inches deep at a certain rate of speed.

"It takes a while to learn," he said.

The leap in technology means that many of the workers who once toiled on the old machines, and had become proficient on them, can no longer find jobs.

"You don't see anyone advertising for just a tool and die maker anymore," said Tom Whitmore, 59, a tool and die maker who was laid off in 2009 after 33 years at a nearby auto parts maker. "They want CNC skills. For most of them, I can't apply."

Whitmore and two of his co-workers are attending classes at Lake Michigan College to attain an associate's degree in machine tool technology.

"I'm a statistic," said Mark Miller, 36, whose home went into foreclosure after he was laid off as a production technician. "I came straight out of high school and found a job. But these days, you have to have some technical skills. When I get out of here, the idea is to be able not just to run a machine, but to program it."

One of the other key factors for the shortage, however, is the loss of baby boom workers. With the downsizing in the industry and years of little growth, many manufacturers have a graying workforce. At Boeing, 28 percent of the company's 31,000 machinists are older than 55 and eligible for retirement, a union official said.

"The company has to be ready for the attrition," said Connie Kelliher, spokesperson for the International Association of Machinists district in Seattle.

But attracting younger workers onto the factory floor can be difficult. Machine shop classes have been cut in some high schools. Many high schools, moreover, would rather focus on helping children get into four-year colleges than preparing them for vocational pursuits.

"It's a glamor issue," said Dave Van Dam, 37. "The kids come in here and see a dirty, loud place. We get oil on ourselves. Then they go upstairs and they see the designers in their cubicles with two screens and headphones on listening to music.

"Plus, there's the uniform we wear on the floor," said Van Dam, dressed in work pants and a shirt with his name embroidered in blue stitching on the chest. "You go into a restaurant dressed like this, and you get treated different than if you have a suit on."

The funny thing is, Van Dam said, that a skilled machine operator makes more than a designer. Pay for skilled operator-programmers runs from $18 to $28 per hour; the designers upstairs make $14 to $24.

Matt Bickel, a barrel-chested welder with an Indianapolis Colts sweatshirt, safety glasses, boots and stained jeans, echoed other workers on the factory floors here when asked how there could be a shortage of factory workers.

"A bunch of lazy Americans don't want to get their hands dirty anymore," he said. "They want an office job."