The government shutdown dealt yet another blow to airport security on Sunday, with officials at Houston’s George Bush Intercontinental Airport announcing they have been forced to close the security checkpoint in one terminal due to a shortage of TSA agents to screen passengers.

The decision comes two days after airport officials in Miami took similar precautions over the weekend, announcing that one of the smaller terminals at Miami International Airport would close early each day starting on Saturday.

In Houston, officials at the main airport serving the nation’s fourth largest city announced that “due to staffing issues associated with the partial shutdown of the federal government,” a TSA checkpoint and the ticketing counter in Terminal B closed at 3:30 p.m and would remain closed for the rest of the day. After assessing the situation, authorities said Sunday night that the terminal would remain closed at least into Monday. The officials encouraged passengers to “arrive early and give themselves extra time to check in for their flights and to clear the security checkpoints.”

“We are aware of the situation at Houston Bush Airport. As TSA has stated previously, airports in certain locations will begin exercising consolidation options during peak periods,” TSA spokesman Michael Bilello told The Daily Beast. “These decisions will be made at the local level. If you plan to fly, please contact your airport to learn more about wait times and closures.”

The news in Houston came as the number of agents who called in sick on Sunday more than doubled from the same day a year ago from 3.2 percent to 7.7 percent, Bilello said. But he stressed that “most importantly, security standards remain uncompromised at our nation’s airports.”

The nation’s 51,000 TSA agents have been manning checkpoints without pay since the shutdown began on Dec. 22, and like many other federal employees missed their first paycheck on Friday.

But because they’re considered employees essential to security of the country, they’re legally required to keep working without a salary. As the The Daily Beast previously reported, many have started calling in sick in protest, and some have quit their jobs entirely. And as the shutdown meanders on with no end in sight, it’s only getting worse.

“Listen, I love my job and I have been willing to work for free as people in Washington sort everything out,” one worker told The Daily Beast, noting that at least 15 of his coworkers had called out sick since the shutdown began.

“But how long is this going to take? I have a newborn. I can barely afford to miss this pay period. I don’t want to lose my job but I also don’t want to lose my apartment, you know?”

Throughout the shutdown, government officials have added insult to injury. The U.S. Office of Personnel Management suggested that furloughed workers do chores for their landlords to help pay rent. The Coast Guard suggested they hold garage sales. And on Sunday, Sen. Lindsey Graham labeled the shutdown, which has left nearly 800,000 federal workers without pay, “inconvenient.”

“How much damage does that do if this government shutdown goes on for weeks even into next month?” he asked.

Hydrick Thomas, head of the American Federation of Government Employees' TSA Council, predicted the attrition of federal workers in a statement Tuesday.

“Some of them have already quit and many are considering quitting the federal workforce because of this shutdown,” Thomas said. “The loss of officers, while we're already shorthanded, will create a massive security risk for American travelers since we don't have enough trainees in the pipeline or the ability to process new hires. Our TSOs already do an amazing job without the proper staffing levels, but if this keeps up there are problems that will arise—least of which would be increased wait times for travelers.”

Unlike their airport counterparts, the unpaid air traffic controllers are moving to “educate the public about what is happening” instead of protesting. The National Air Traffic Controllers Association also filed a lawsuit against the administration Friday to force the government to pay its members for the hours they’ve worked since the shutdown began.

Doug Church, Deputy Director of Public Affairs for the National Air Traffic Controllers Association, told The Daily Beast on Sunday that air traffic controllers will begin a “leafleting campaign” early this week.

On Tuesday, air traffic controllers for Charlotte Douglas International Airport, Minneapolis−Saint Paul International Airport, and Indianapolis International Airport will engage in these leafleting campaigns, Church said.

“It is illegal to walk off the job. Our members are continuing to go to work to do their important public safety jobs but this situation is tremendously distracting and stressful,” Church said, emphasizing this nation-wide campaign is not a “strike.”

The campaign will happen off the clock, Church said, to ensure the safety of passengers.

“Controllers participating in the leafleting campaign will do so on their own personal time,” he said. “They are continuing to work their shift as scheduled.”

More airports are forthcoming about the campaign, he said, and the union anticipates more as the week progresses.