There are currently about 5,100 Guard troops in Washington, and they were scheduled to leave this weekend.
Early on, Guard members were briefly forced to take rest breaks and meals in a nearby cold garage, sparking outrage within the Biden administration.
In addition, Guard members complained of bad food, and some said they became sick.
On Monday, Kirby said about 50 Guard troops had been treated for gastrointestinal issues, out of the 26,000 that deployed to Washington.
AdActing Capitol Police Chief Yogananda Pittman made the request to have the Guard members stay on, setting off a series of discussions with the Pentagon and National Guard leaders.