One of President Joe Biden's dogs apparently deposited the pile of poo in the hallway outside the Diplomatic Reception Room, just off the South Lawn, on Wednesday.

Reporters accompanying Jill Biden on a trip to California spotted the brown stuff on the red-carpeted hallway as they waited just inside the mansion to be escorted to the first lady's motorcade.

It was unclear which pooch — Major or Champ — dropped the poo.

Earlier this week, Major, the younger dog, was involved in his second biting incident in March.

Michael LaRosa, a spokesperson for Jill Biden, said the 3-year-old German shepherd "nipped someone while on a walk" on Monday. The person, who was not identified, was examined by the White House medical staff and returned to work without injury, LaRosa said.

He said Major was still adjusting to White House life. Both dogs had lived with the Bidens in Delaware before Joe Biden took office.

Champ, 12, and Major recently had returned to the White House after Major caused a minor injury to a Secret Service employee on March 8. They had spent some down time back in Delaware, and the president had said Major was being trained.

Champ and Major were later seen on the South Lawn before the first lady's motorcade departed Wednesday. Major was on a leash while Champ roamed freely.

What happened Wednesday wasn't the first known instance of dog poop inside the White House, given the long history of presidential dog ownership.

President Barack Obama's dog Sunny liked to sneak off and poop in the mansion, his wife, Michelle, once said.

Here's a look back at some of the presidential pets that have roamed the White House: