Watch: Thanksgiving turkeys prep for White House pardon

The pair of Thanksgiving turkeys were due at the White House on Monday to play their part in what has become an annual tradition: a president sparing turkeys from becoming someone's holiday dinner.

“The birds will be right around 42 pounds when they're presented to the president,” Steve Lykken, chairman of the National Turkey Federation and president of the Jennie-O Turkey Store, said.

After US President Joe Biden officially pardons Liberty and Bell, they will be returned to their home state to be cared for by the University of Minnesota's College of Food, Agricultural and Natural Resources Sciences.

The tradition dates back to 1947 when the National Turkey Federation first presented a National Thanksgiving Turkey to President Harry Truman.

Back then, the gobbler was given for the first family's holiday consumption.

But by the late 1980s, the tradition had evolved into an often humorous ceremony where the birds are pardoned, spared from becoming the centrepiece of someone's Thanksgiving table.

The annual turkey pardoning ceremony serves as the unofficial opening of the holiday season in Washington.