Washington CNN  — 

Vice President Mike Pence was put on standby to temporarily assume the powers of the presidency during President Donald Trump’s unannounced visit to Walter Reed hospital in November 2019, according to a copy of New York Times reporter Michael Schmidt’s forthcoming book obtained by CNN.

Trump had undergone a “quick exam and labs” as part of his annual physical out of anticipation of a “very busy 2020,” the White House had said of the trip at the time.

Schmidt writes, however, that he learned “in the hours leading up to Trump’s trip to the hospital, word went out in the West Wing for the vice president to be on standby to take over the powers of the presidency temporarily if Trump had to undergo a procedure that would have required him to be anesthetized.” Schmidt does not specify the sourcing for this reporting beyond “I learned.”

Pence on Tuesday disputed that he had been placed on standby during the visit, telling Fox News’ Bret Baier that “I’m always informed of the President’s movements – whether it was on that day or any other day, I’m informed. But there was no, there was nothing out of the ordinary about that moment or that day.”

When pressed on whether he had been placed on standby, Pence replied, “I don’t recall being told to be on standby. I was informed that the President had a doctor’s appointment,” adding that “part of this job is you’re always on standby, you’re vice president of the United States.”

While Pence did not ultimately assume the powers of the presidency, according to Schmidt, the account raises fresh questions about the reason for Trump’s unscheduled visit.

The visit did not follow the protocol of a routine presidential medical exam, a person familiar with the matter told CNN at the time. Medical staff at Walter Reed did not get a staff-wide notice about a presidential visit to the medical center in Bethesda, Maryland, ahead of Trump’s arrival, according to that source.

Typically, Walter Reed’s medical staff would get a general notice about a “VIP” visit to the medical center ahead of a presidential arrival, notifying them of certain closures at the facility. That did not happen this time, indicating the visit was a non-routine visit and scheduled at the last minute.

The source told CNN it was possible a small group of doctors involved in Trump’s medical exams were notified before Trump arrived, but that all medical staff at Walter Reed would typically be aware if the President was arriving for a routine medical exam.

Trump tweeted the morning after his visit, “Everything very good (great!)” regarding his health.

This story has been updated to include reaction from Pence.

CNN’s Jeremy Diamond and Kevin Liptak contributed to this report.