Mike Pence was put on standby to assume the presidency during Donald Trump's unannounced visit to Walter Reed Hospital, new book claims

The White House had Vice President Mike Pence on stand by in November last year when President Donald Trump made an unplanned visit to Walter Reed National Military Medical Center, a new book claims.

In November 2019, the president made an unannounced trip to the hospital for 'quick exam and labs' as part of his annual physical exam out of anticipation of a 'very busy 2020,' the White House said at the time.

But the surprise nature of the trip lead to questions about the president's medical condition.

And in Michael Schmidt's 'Donald Trump v. the United States,' out on Tuesday, the author writes Pence was on standby if the president had to undergo a procedure that would have required anesthesia.

The White House had Vice President Mike Pence on stand by in November last year when President Donald Trump made an unplanned visit to Walter Reed National Military Medical Center

President Trump in route to Walter Reed on Saturday, November 16, 2019, for a visit the White House said was part of his routine physical 

It is the job of the vice president to assume executive powers should the president be incapacitated in some way, according to the 25th amendment to the Constitution.

Section Three of 25th Amendment 

Whenever the President transmits to the President pro tempore of the Senate and the Speaker of the House of Representatives his written declaration that he is 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. 

Schmidt writes, according to a New York Times review of his book: The White House wanted Mike Pence '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.' 

Pence obviously never had to step in.  

The last time a vice president took such a step was Dick Cheney in July 2007 when George W. Bush underwent a colonoscopy and was under sedation.

In a statement at the time of Trump's hospital visit, then-White House press secretary Stephanie Grisham said that Trump had undergone a 'quick exam and labs' and that he 'remains healthy and energetic without complaints.' 

She also said that the president had taken advantage of a 'free weekend' in Washington to 'begin portions of his routine annual physical exam.' 

But Trump's trip raised so many questions about the then 73-year-old's health that the White House released a memo a few days later denying 'speculation' that he had been treated for a medical emergency.  

Dr. Sean Conley, the president's personal physician, wrote that Trump's 'interim checkup' had been 'routine,' and was only kept secret because of 'scheduling uncertainties.'

'Despite some speculation, the President has not had any chest pain, nor was he evaluated or treated for any urgent or acute issues,' Conley wrote in the memo. 'Specifically, he did not undergo any specialized cardiac or neurologic evaluations.'

Michael Schmidt's 'Donald Trump v. the United States,' is out on Tuesday

The full results of the president's physical were released in June and he was reported to be 'healthy.' 

Schmidt's book, meanwhile, 'tells the dramatic, high-stakes story of those who felt compelled to confront and try to contain the most powerful man in the world as he shredded norms and sought to expand his power,' according to its Amazon.com description.

It is the latest in a spat of books to come about the Trump administration, including Bob Woodward's upcoming book 'Rage' and Michael Cohen's upcoming 'Disloyalty.' 

There are also recently published books from Mary Trump, about her uncle's upbringing, and former National Security Adviser John Bolton about his White House tenure.  Even the first lady has not been immune. Stephanie Winston Wolkoff's memoir about her work with Melania Trump, the two were long time friends, comes out Tuesday.

The book also documents the tenure of former White House general counsel Don McGahn, who shepherded Trump's two Supreme Court nominees successfully through the Senate before departing the administration. 

McGahn then got caught up in special counsel Robert Mueller's investigation and featured prominently in that report, which found the Trump campaign did not collude with Russia in the 2016 election but left it an open question as to whether or not the president attempted to obstruct the probe. 

The book claims McGahn left the White House after Trump granted clemency to Alice Johnson: 'It was only after Trump granted a woman clemency at Kim Kardashian's request that McGahn knew he truly had to leave the White House. He could no longer abide the accumulation of Trump's actions.'

The last time a vice president took over for a president was Dick Cheney in July 2007 when George W. Bush underwent a colonoscopy and was under sedation

Schmidt's book documents the tenure of former White House general counsel Don McGahn

Book reports McGahn left the White House after President Trump gave clemency to Alice Johnson (standing to the right of Trump) at the behest of Kim Kardashian

President Trump gave Alice Johnson a full pardon last week

Other random details in the book include that Senate Republican Mitch McConnell once fell asleep during a classified briefing on Russia.

And, on Feb. 23, 2018, McGahn sent a two-page memo to then-Chief of Staff John Kelly arguing that Jared Kushner's security clearance needed to be downgraded, the book reports according to Axios.