O’Connor has served as Biden’s primary care physician since 2009, when he was appointed physician to the vice president and was chosen by Biden for the new role due to their long history, and personal relationship, according to a White House official.
O’Connor served 22 years in the Army, including tours of duty with the 82nd Airborne Division, 75th Ranger Regiment, and United States Army Special Operations Command, and over a decade at the White House-- an eight-year extension at Biden’s request to what was supposed to be a three-year gig.
O’Connor retired from the military following the Obama administration and continued as Biden’s doctor while serving as the Founding Director of Executive Medicine at George Washington University.
According to Dr. Lud Deppisch, a retired pathologist and author of “The White House Physician: A History from Washington to George W. Bush,” it's standard operating procedure for a president to choose their personal physician, but it's rare that a president comes into office with a doctor that has cared for them for over a decade.
“It's difficult to get their previous personal physician to Washington for two reasons: The pay stinks, comparatively. And secondly, usually the care of the president is not all that interesting. Not much goes wrong. Under George W. Bush and Barack Obama, nothing much happened,” Deppisch said.
But Deppisch contends while it might not be the most glamorous position, it's no less important.
“They're around a lot-- it's quite a significant and tireless responsibility,” he said.
The Biden administration will be the third White House O’Connor has served. It's one that could face increased scrutiny over the president’s health, given Biden’s distinction as the oldest president ever elected.
O’Connor played a role in Biden’s campaign as well, increasingly so after Trump was diagnosed with COVID-19 shortly after the first presidential debate in September. He also helped with the care of Biden’s fractured foot, which he sustained while playing with his dog over the Thanksgiving holiday.
O’Connor also conducted and released the only physical & medical report for Biden during his campaign in December 2019: a three-page summary that declared Biden “a healthy, vigorous, 77-year-old male, who is fit to successfully execute the duties of the presidency."
At the time of the report, Biden was under treatment for four different conditions, including non-valvular atrial fibrillation (A-fib)--a type of irregular heart rhythm, hyperlipidemia-- higher concentrations of fats or lipids in the blood, gastroesophageal reflux, and seasonal allergies.
The most notable health incident in Biden's past, according to O'Connor's report, were the two cranial aneurysms that he suffered in 1988. No additional report on Biden's health was released during the campaign.
On the campaign trail, the 78-year-old often faced questions about how he would handle the rigors of the job at his age.
“Look, it’s a legitimate thing to be concerned about my age. Just like it was a legitimate concern when I was 29 whether I had the judgment to be a U.S. Senator. I think it’s totally legitimate. The only thing I can say is watch, watch. Check my energy level, determine whether I know what I’m talking about,” Biden told voters in Newton, Iowa, in 2019.
According to Deppisch, the personal physician to the president usually departs with the change of administrations. Trump’s second White House Physician, Dr. Sean Conley, is expected to move to a faculty role at the Uniformed Services University of the Health Sciences, according to the White House.
"In doing so, you know, it came off that we were trying to hide something, which wasn't necessarily true,” Conley said in October 2020.
Rear Admiral Dr. Ronny Jackson, who also worked in the White House medical unit under three administrations, including as Obama and Trump’s personal physician, also faced criticism after he gave a glowing readout of Trump’s 2018 physical -- an analysis that was questioned by outside experts.
But those closer to Biden do not expect similar situations to arise under O’Conner.
A source close to the president said Biden would never ask O’Connor to lie for him, and O’Connor would never offer. The two wouldn’t want to disappoint each other, the source added.
This report was featured in the Monday, Jan. 25, 2020, episode of “Start Here,” ABC News’ daily news podcast.
"Start Here" offers a straightforward look at the day's top stories in 20 minutes. Listen for free every weekday on Apple Podcasts, Google Podcasts, Spotify, the ABC News app or wherever you get your podcasts.