With the US government shutdown entering its 22nd day, the longest closure in the nation’s history, the Transportation Security Administration (TSA) has begun lessening security measures at various airports around the US.

According to a statement, Miami International Airport will shut down one of its courses (Concourse G) for several days beginning Saturday, as TSA officials have been calling in sick at twice the regular rate, according to multiple sources.

United Continental Holdings Inc., which operates flights departing Concourse G, will try to ensure that customers are not impacted by the closure, according to reports.

"We will work to ensure we do everything we can for our customers and we do not expect any operational impact," Frank Benenati, a United spokesperson, told Bloomberg.

Over 51,000 TSA security agents have been working without pay since December 22, after Congress refused to throw its support behind a bill to satisfy US President Donald Trump's $5.6 billion demand for a 2000-mile, 30-foot-tall, concrete border wall with Mexico.

Currently, nine of 15 federal departments, as well as dozens of other agencies and federal programs, have closed or decreased services due to the refusal of the president to sign a budget bill that does not include spending for his wall.

In addition, around 800,000 federal employees have been on furlough or are being forced to continue working without pay, costing the US economy an estimated several billion dollars to date.

On Thursday, the TSA saw a 55 percent increase in the number of employees calling in sick compared to a year ago, according to spokesperson Michael Bilello, Bloomberg reported.

Although travelers have not yet been impacted by airport screening, it could easily become intractable, according to Christopher Bidwell, a senior vice president at the Airports Council International-North America in Washington, cited by Bloomberg.

"We're very concerned that the current situation with government employees going without pay is unsustainable in the long term," Bidwell told Bloomberg. "We certainly have to be mindful of the potential for cascading operational impacts."

Other federal workers involved with key airport security and operations whio are going without pay include air traffic controllers and airplane safety inspectors.

Last week, Trump said he was "very strongly" considering declaring a national emergency if Democrats in Congress refuse to rubber stamp the money for his wall.

"We're looking at a national emergency, because we have a national emergency," Trump told reporters outside the White House, in spite of overwhelming evidence that the president's dire warning is not based in fact.

"We have a crisis at the border of drugs, of human beings being trafficked all over the world,' Trump raved, adding, "They're coming through. And we have an absolute crisis, and of criminals and gang members coming through. It is national security. It's a national emergency."