President Joe Biden briefly transferred power to Vice President Kamala Harris on Friday to undergo a routine colonoscopy at Walter Reed National Military Medical Center before resuming his duties, the White House said.

Biden drove early Friday to the medical center in the Washington suburbs for his first routine physical exam as president. Press secretary Jen Psaki said Biden would be under anesthesia during the colonoscopy and temporarily transferred power to Harris. Psaki said Biden resumed his duties after speaking with Harris and White House chief of staff Ron Klain at approximately 11:35 a.m.

Harris, the first woman, person of color and person of South Asian descent to be vice president, made history during the short time she served as acting president. She was scheduled to travel to Ohio later Friday, after Biden resumed his duties.

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“As was the case when President George W. Bush had the same procedure in 2002 and 2007, and following the process set out in the Constitution, President Biden will transfer power to the Vice President for the brief period of time when he is under anesthesia,” Psaki said before Biden’s colonoscopy. “The Vice President will work from her office in the West Wing during this time.”

Biden, 78, had his last full exam in December 2019, when doctors found the former vice president to be “healthy, vigorous” and “fit to successfully execute the duties of the Presidency,” according to a doctor’s report at the time. Biden, who turns 79 on Saturday, is the oldest person to serve as president, and interest in his health has been high since he declared his candidacy for the White House in 2019.

Dr. Kevin O’Connor, who has been Biden’s primary care physician since 2009, wrote in a three-page note that the then-presidential candidate was in overall good shape.

In that report, O’Connor said that since 2003, Biden has had episodes of atrial fibrillation, a type of irregular heartbeat that’s potentially serious but treatable. At the time, O’Connor cited a list of tests that showed Biden’s heart was functioning normally and his only needed care was a blood thinner to prevent the most worrisome risk, blood clots or stroke.

Biden had a brush with death in 1988, requiring surgery to repair two brain aneurysms, weak bulges in arteries, one of them leaking. Biden has never had a recurrence, his doctor said, citing a test in 2014 that examined his arteries.

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Pursuant to the 25th Amendment to the Constitution, Biden signed letters to Sen. Patrick Leahy, who’s president pro tempore of the Senate, and to House Speaker Nancy Pelosi at 10:10 a.m., saying he would be unable to discharge his duties while under anesthesia, making Harris the acting president. Biden sent them each another letter upon the conclusion of the procedure to resume his duties.

On Friday afternoon, Biden is scheduled to take part in the annual pardoning of the national Thanksgiving turkey.

When Biden took office he brought O’Connor back to the White House to continue serving as his doctor, and O’Connor was expected to lead a team of experts in conducting Biden’s physical exam Friday.

Once the COVID-19 pandemic emerged in early 2020, Biden’s team took intense steps to keep the then-candidate and now-president healthy as the virus raged and took a disproportionate toll among older populations. Biden received his first dose of the COVID-19 vaccines in December 2020 and his second dose just two weeks before taking office. He received a booster dose, which regulators say provides more enduring protection, in late September.

The White House said Biden would authorize the release of a medical report, as is customary for presidents and presidential candidates. Former President Donald Trump, 75, was sharply criticized for releasing only cursory details on his health while running and serving in the White House, including concealing the seriousness of his COVID-19 illness a month before the 2020 presidential election.