Chris Alig, with his wife Heather in Canton, Illinois, considers himself a middle-class family man. But to maintain his home and lifestyle, Alig needs at least 20 hours a week of overtime. Many factory workers are facing the same situation.

CHICAGO — Jim Ellis had a job with benefits but gave it up for a shot at something with a bright future, if he could just get his foot in the door.

In this part of the country, that meant he wanted to work for Caterpillar, the construction equipment powerhouse. Now, Ellis is on the morning shift at the company’s East Peoria, Ill., plant, installing fenders on tractors and working on hydraulic lines, a manufacturing job description that once promised an American middle-class lifestyle.

The reality for Ellis is nothing like that.

With the new job he started in January, Ellis’s pay jumped by $5 to $15.57 per hour, but he has no medical benefits for himself or his 3-year-old daughter, custody of whom he shares with his ex-girlfriend. Between rent and child support, he acknowledges falling back on his parents for support.

“If you talk to my mom and dad, they would tell you I’m an idiot because I’m barely making ends meet,” Ellis, 38, said.

Reflecting on his pay, Ellis recalled the years he worked as an assistant manager at a fast food restaurant. “It was one of the easiest jobs I’ve had,” he said. It was also the best-paying job he’s had. He earned up to $34,000 a year — a little more than $16 an hour.

His move to Caterpillar hardly evokes the kind of jobs most people think about when they hear President Barack Obama or his challenger, Mitt Romney, talk about bringing back manufacturing. The days when workers earned enough money to buy a car, a boat or a second home while supporting their families no longer exist for a growing number of people employed in manufacturing.

Factory jobs can still be good, but in the past three decades, benefits have eroded and pay has stagnated for many, or even fallen. Some entry-level manufacturing jobs pay so little that workers depend on government aid to feed their families and pay for health care.

Take Charles Montgomery. Until he was laid off in mid-September, he worked for a staffing agency that supplies labor to Caterpillar. Montgomery, 28, was paid $8.75 an hour as a forklift operator and put in as many as 70 hours a week to support his three children and fiancee and relied on government aid to buy food.

Wages have declined across many industries, including manufacturing, as unions have lost their bargaining clout, according to the Economic Policy Institute, a pro-labor think tank based in Washington. Between 1973 and 2011, the median hourly compensation of workers, including wages and benefits, rose only 10.7 percent; most of that increase occurred in the ’90s, according to the institute.

Robert Bruno, a professor of labor and employment relations at the University of Illinois-Chicago, said earnings of newer manufacturing jobs “are not poverty wages, but they are not middle class. If the jobs don’t pay sufficiently better, sadly, it will turn the manufacturing sector into another low-wage market, and we already have many of those,” he said.

Factory wages could fall even further, predicts Howard Wial, executive director of the Center for Urban Economic Development and a nonresident senior fellow at the Brookings Institution. Historically, Wial said, unionized workers have accepted concessions in bad economic times by counting on getting something back during good years. But that’s no longer necessarily true.