Mr. Biden has been on an informal farewell tour in recent days. He delivered his final foreign policy speech at the State Department Monday and a speech on his conservation legacy Tuesday. He's also expected to speak Thursday at a Pentagon commander-in-chief farewell ceremony.

President Biden released a farewell letter Wednesday, saying that “It has been the privilege of my life to serve this nation for over 50 years."

Retiring President Joe Biden said it was the “privilege of my life” to serve in politics as he released his farewell letter — days before President-elect Donald Trump is set to take