They are among the overlooked, the underappreciated and still, the unpaid.

They clean toilets, mop floors and maintain security.

They work in federal buildings but are not federal employees.

They are lower-wage government contractors.

It’s been one year since the longest partial government shutdown — at 35 days — ended. Federal employees received back pay for time missed, but many contractors still have not.

“We’re just federal contractors, so we’re like the bottom of the barrel,” said Michelle Serrano, 44, a security officer at the Smithsonian’s National Museum of the American Indian branch in New York. “We’re not considered federal workers.”

House Democrats approved a bill in June, with no Republican support, that would have provided people like Serrano back pay.

“Federal contract service workers, many of whom live paycheck to paycheck, missed more than a month of pay over the course of the government shutdown and are still struggling to deal with the economic ramifications,” the bill’s sponsor, Rep. Ayanna Pressley (D-Mass.), said by email. “The federal government relies on these hardworking men and women to keep our government buildings running and we have an obligation to do right by them.”

Sen. Chris Van Hollen (D-Md.) fought for the bill in the Republican-controlled Senate. It went nowhere.

“Since last year’s Trump shutdown I have repeatedly pushed my Republican colleagues to provide back pay to federal contract employees, many of whom make up janitorial and support staffs,” he said in a statement. “These men and women were stranded without pay for weeks through no fault of their own, and their unpaid bills did not go away when the shutdown ended. It is shameful that Republicans and the Trump Administration have blocked our attempts to right this wrong, and I will continue working to address this issue.”

Two key Republicans — Sen. Ron Johnson (Wis.) and Rep. Mark Meadows (N.C.), respectively chairman and ranking minority-party member of congressional panels that oversee the federal workforce — did not respond to requests for comment.

The workers, not affluent to begin with, still feel the shutdown’s bite.

Serrano estimates she lost about $3,000 because Congress failed to keep all agencies working. Her family, including daughter Elicia, suffered. After Elicia completed her first semester in college, “we weren’t able to afford the second semester because of the shutdown,” Serrano said. “That was a setback. She had to get a job.”

Serrano, like all contractors, is employed by a private firm doing work for the federal government, but their beef is with various agencies, not the companies.

Which government contractors were paid “depends on the agency,” said Jaime Contreras, vice president of 32BJ, a regional arm of the Service Employees International Union. It represents about 650 contract workers still seeking back pay.

“The reality is that all the agencies actually have the flexibility to pay their contractors because their budget was preapproved a year before. So some agencies did and some agencies didn’t,” he said.

Serrano and others did not get paid because the Smithsonian did not pay the contracting company.

“In the event of a government shutdown and our buildings are closed, we will not pay the security firm,” said Linda St.Thomas, chief spokesperson for the Smithsonian Institution.

That makes sense to agency number crunchers, but it’s lower-paid folks like Lila Johnson who get crunched.

She spent 50 of her 72 years cleaning buildings, the last two decades as an Agriculture Department contractor. Painful arthritis has swollen her hands and forced her retirement in November, making back pay even more important.

“I’m not working,” she said, “so I really, truly need the money” — for herself and the two great-grandchildren she is raising.

“My credit cards got maxed out, so I couldn’t use them anymore. I did the best I could,” Johnson said.

That included reluctantly borrowing money from the cash value of her life insurance policy. She did that only once before, “to help with the burial of my nephew.”

Agriculture’s response is much like the Smithsonian’s. If the government did not pay the contractor because the agency’s funding lapsed, the USDA’s statement said, “and there was no work completed, the contractor did not get paid by the government.”

That logic does not apply to federal employees. Congress provided them back pay. Does this leave federal contractors feeling cheated?

“I do. I really do,” said Arleja Stephens, 35, who works security and concessions at the Lincoln Memorial. “Nothing just runs by itself. You have a whole team of people.” But some people don’t really appreciate that.

“No one is even thinking that when you go to the bathroom, the bathroom is clean,” Stephens added. “When you go to the cafeteria, there’s people there who serve you food — just a whole host of things that people just take for granted.”

Like the assumption that the lowest paid don’t need back pay.