They are 230,000 strong, yet often seem invisible.

They back the military with critical skills, yet they are frequently forgotten.

Their collars are blue, which increasingly matches their mood.

The wage-grade employees in the federal government don’t get much notice, but this generally quiet group now is making noise.

Employees covered by the Federal Wage System continue to labor in the cold of the three-year freeze on basic pay rates that ended with the calendar year for most workers. The 1 percent pay raise provided to their colleagues did not include wage-grade staffers.

These are the government’s blue-collar workers.

Wage-grade workers are not covered by the law that allows the president to set a pay raise amount for the much larger General Schedule employees. Generally, Wage System pay increases have been included in appropriations legislation, and that might happen this year, too.

“The administration supports extending the 1 percent pay increase to wage-grade employees and urges the Congress to include the necessary language in the final appropriations legislation,” said Beth Cobert, deputy director for management at the Office of Management and Budget. “The pay increase is not something that can be extended administratively. It requires congressional action.”

So far, however, those in the know don’t know what’s going to happen, and that leaves the wage-grade workers nervous. The best anyone can say is that a raise could be included in legislation Congress might consider this week. No opposition has emerged.

“We believe getting language in the omnibus spending bill is our best shot at getting WG federal workers the 1 percent adjustment in 2014 that they deserve,” said Randy L. Erwin, legislative director of the National Federation of Federal Employees, calling it “our very first priority.” “It is inexcusable for Congress to authorize a pay adjustment for white-collar federal employees but force blue-collar workers to suffer yet another year of frozen pay. This inequity must be rectified.”

For blue-collar workers, it’s about more than pay. It’s also a matter of respect.

“I have been a federal employee for 10-plus years and during that time GS and WG employees have always been separated in respect to the way they have been treated,” said Cebron E. O’Bier Jr., an electronics employee at the Red River Army Depot in Texarkana, Tex. He’s also president of the NFFE local. “WG employees do not get the same respect as GS employees.”

Wage-grade workers have a range of occupations, from aircraft mechanic to high-voltage electrician to welder. Their average pay in 2013 was $53,043, compared with $74,709 for GS staffers. Wage-graders work in more than 40 agencies, but 70 percent are employed by the Defense Department.

Rep. Matthew Cartwright (D-Pa.) has introduced bills that would provide a wage-grade raise equivalent to what GS workers receive and align the boundaries used in determining the locality pay rates of the two classification systems. Currently, GS white-collar employees at the Tobyhanna Army Depot in his district are in the top-dollar New York zone, but pay for the depot’s blue-collar workers is based on Scranton wages.

Labor leaders say the difference in locality classification for workers in the same place can make a big difference, as much as $3 an hour.

“No private employer that varies pay by locality draws different boundaries for salaried and hourly workers, and the federal government should follow suit,” said J. David Cox Sr., president of the American Federation of Government Employees. “Treating salaried and hourly workers differently in this context is unfair and inefficient. Federal workers in the skilled trades commute along the same routes and face the same living costs as their salaried co-workers. It is unconscionable that, once they arrive at work, their employer pretends they are in different locations.”

Twitter: @JoeDavidsonWP

Previous columns by Joe Davidson are available at wapo.st/JoeDavidson.

Staff writer Eric Yoder contributed to this report.