While President Joe Biden underwent a colonoscopy, he transferred power to Vice-President Kamala Harris, making her the first woman to be acting president in the history of the U.S., reports CNN. Jen Psaki, White House Press Secretary, explained that the temporary transfer of powers for medical reasons was not unprecedented and it coincides with procedures laid out in the US constitution. "As was the case when President George W. Bush had the same procedure in 2002 and 2007," she said in a statement.

To complete the official transfer of presidential powers to Harris, Biden sent a letter to House Speaker Nancy Pelosi and Democratic Sen. Patrick Leahy of Vermont, who serves as the president pro tempore of the Senate, right before going under anesthesia.

"Today I will undergo a routine medical procedure requiring sedation,” the letter read. “In view of present circumstances, I have determined to transfer temporarily the powers and duties of the office of President of the United States to the Vice President during the brief period of the procedure and recovery."

According to Section 3 of the 25th Amendment to the US Constitution, a sitting President can send a letter to the speaker of the House of Representatives and the president pro tempore of the Senate saying they are "unable to discharge the powers and duties of his office, and until he transmits to them a written declaration to the contrary, such powers and duties shall be discharged by the Vice President as Acting President."

A separate letter was drawn and sent after the procedure, Harris effectively transferred power back to Biden.

"In accordance with the provisions of section 3 of the Twenty-Fifth Amendment to the United States Constitution, I hereby transmit to you my written declaration that I am able to discharge the powers and duties of the Office of the President of the United States and that I am resuming those powers and duties," the letter, that was sent to both Pelosi and Leahy, reads.

As the nation's first female, first Black, and first South Asian vice president, Harris made history again as the first woman—albeit temporarily—to be acting president of the United States.